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Seed classification system for marijuana

The Biology of Cannabis sativa L. (Cannabis, hemp, marijuana)

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1 General administrative information

1.1 Background

The Canadian Food Inspection Agency’s Plant and Biotechnology Risk Assessment (PBRA) Unit is responsible for assessing the potential risk to the environment from the release of plants with novel traits (PNTs) into the Canadian environment. The PBRA Unit is also responsible for assessing the pest potential of plants imports and plant species new to Canada.

Risk assessments conducted by the PBRA Unit require biological information about the plant species being assessed. Therefore, these assessments can be done in conjunction with species-specific biology documents that provide the necessary biological information. When a PNT is assessed, these biology documents serve as companion documents to Dir94-08: Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits.

1.2 Scope

This document is intended to provide background information on the biology of Canabis sativa L.

  • its identity
  • geographical distribution
  • reproductive biology
  • related species
  • the potential for gene introgression from C. sativa into relatives
  • details of the life forms with which it interacts

Unless specified otherwise, information provided hereinafter concerns the whole genus Cannabis.

Such information will be used during risk assessments conducted by the PBRA unit. Specifically, it may be used to characterize the potential risk from the release of the plant into the Canadian environment with regard to

  • weediness/invasiveness
  • gene flow
  • plant pest properties
  • impacts on other organisms
  • impact on biodiversity

2 Identity

2.1 Name(s)

Cannabis sativa L. Footnote 23

2.2 Family

2.3 Synonym(s)

Synonyms for C. sativa Footnote 23 include:

  • Cannabis sativa subsp. sativa
  • Cannabis indica Lam.
  • Cannabis sativa subsp. indica (Lam.) E. Small & Cronquist
  • Cannabis ruderalis Janisch.

2.4 Common names

Cannabis sativa is commonly known as cannabis, hemp, Indian hemp, marihuana, and marijuana Footnote 23 Footnote 199 .

2.5 Taxonomy and genetics

C. sativa belongs to the Cannabaceae family Footnote 23 . The Cannabaceae family includes 12 genera and about 102 species Footnote 24 , including other economically important species such

  • Humulus lupulus L. (hop)
  • Pteroceltis tatarinowii (blue sandalwood) Footnote 23

C. sativa is diploid (2n = 20) Footnote 193 .

Taxon Scientific name and common name
Kingdom Plantae (plants)
Subkingdom Tracheobionta (vascular plants)
Superdivision Spermatophyta (seed plants)
Division Magnoliophyta (flowering plants)
Class Equisetopsida
Subclass Magnoliidae
Order Rosales
Family Cannabaceae
Genus Cannabis
Species Cannabis sativa L.

The taxonomic classification of C. sativa has long been a subject of differing opinions and botanical debate Footnote 53 Footnote 136 Footnote 197 Footnote 198 . The majority of botanical treatments describe it as highly diverse but monospecific (that is, one species with intraspecific forms) Footnote 135 Footnote 197 Footnote 199 Footnote 200 Footnote 202 . All forms of C. sativa are naturally diploid and sexually compatible Footnote 202 . The high geographical, morphological, and chemical variation in C. sativa results from extensive selection and domestication towards differing utilitarian needs (fibre, drug, oilseed, etc.). This document considers C. sativa to be monospecific. However, some taxonomists treat Cannabis as polyspecific (that is, multiple species), sometimes with infraspecific forms Footnote 52 Footnote 78 Footnote 111 Footnote 112 Footnote 189 . Recent research demonstrates that marijuana and hemp are significantly differentiated at a genome-wide level, suggesting that the distinction between these two populations is not limited to genes underlying production of the cannabinoid Δ 9 -tetrahydrocannabinol (THC) Footnote 188 Footnote 223 .

Small and Cronquist (1976) Footnote 202 identified a threshold for differentiating between industrial hemp (both fibre-type and oilseed-type) and marijuana (drug-type) forms of C. sativa based on the relative dry weight concentration of THC in the plant’s female inflorescences. Plants accumulating levels above 0.3% Δ 9 -THC are considered marijuana/drug-type C. sativa and plants containing levels below this threshold are considered hemp in North America. In the European Union, the threshold is 0.2% Footnote 12 . Modern assessments of cannabinoid content to delineate the differences between industrial hemp and drug-type varieties combine the total content of THC and Δ9-tetrahydrocannabinolic acid (THCA), given that THCA spontaneously decarboxylates to form THC (see section 4.2.1 Cannabinoids). Small and Cronquist (1976) Footnote 202 have proposed a model for classifying the subspecies and varieties of C. sativa based on the characteristics of the achenes (fruits, commonly called seeds) and tetrahydrocannabinol (THC)/ cannabidiol (CBD) ratios:

1. Cannabis sativa subsp. sativa

Plants of limited intoxicant ability, Δ 9 -THC comprising less than 0.3% (dry weight) of upper third of flowering plants and usually less than half of cannabinoids of resin. Plants cultivated for fibre or oilseed or growing wild in regions where such cultivation has occurred.

Cannabis sativa subsp. sativa var. sativa

Mature fruits relatively large, seldom less than 3.8 millimeters (mm) long, tending to be persistent, without a basal constricted zone, not mottled or marbled, the perianth poorly adherent to the pericarp and frequently more or less sloughed off.

Cannabis sativa subsp. sativa var. spontanea Vavilov

Mature fruits relatively small, commonly less than 3.8 mm long, readily disarticulating from the pedicel, with a more or less definite, short, constricted zone toward the base, tending to be mottled or marbled in appearance because of irregular pigmented areas of the largely persistent and adnate perianth.

2. Cannabis sativa subsp. indica (Lam.) E. Small & Cronquist

Plants of considerable intoxicant ability, Δ 9 -THC comprising more than 0.3% (dry weight) of upper third of flowering plants and frequently more than half of cannabinoids of resin. Plants cultivated for intoxicant properties or growing wild in regions where such cultivation has occurred.

Cannabis sativa subsp. indica var. indica (Lam.) Wehmer

Mature fruits relatively large, seldom less than 3.8 mm long, tending to be persistent, without a basal constricted zone, not mottled or marbled, the perianth poorly adherent to the pericarp and frequently more or less sloughed off.

Cannabis sativa subsp. indica var. kafiristanica (Vavilov) E. Small & Cronquist

Mature fruits relatively small, usually less than 3.8mm long, readily disarticulating from the pedicel, with a more or less definite, short, constricted zone towards the base, tending to be mottled or marbled in appearance because of irregular pigmented areas of the largely persistent and adnate perianth.

The terms “sativa” and “indica” have been applied inconsistently and haphazardly. 2 varieties of drug-type C. sativa were referred to by their common names beginning in the 1980s:

  • C. sativa subsp. indica var. indica (referred to as “sativa”)
  • C. sativa subsp. indica var. afghanica (referred to as “indica”)

Extensive hybridization of these varieties has largely eliminated any distinction between modern strains. However, strains are often labelled as “sativa” or “indica” based on the THC:CBD ratios of the plants; this does not reflect their taxonomic classification or genetic background. Furthermore, “sativa” has been used to refer to either plants with a high THC:CBD ratio or to low-THC hemp forms (“C. sativa“). “Indica” may refer to plants with high THC and CBD or to high-THC, low-CBD forms (“C. indica“) Footnote 139 .

2.6 General description

C. sativa is an herbaceous dioecious annual species displaying considerable variability in phenotypic characteristics; monoecious plants can occur or be developed by breedingefforts Footnote 26 Footnote 81 . Cultivars may show differing shoot architectures dependent on selection towards various utilitarian needs, while plants escaped from cultivation may show degrees of reversion to non-domesticated characteristics. For instance, hemp cultivars selected for fibre production are generally tall, with reduced branching and less woody stem tissue to maximize bast fibre production, whereas drug-type C. sativa varieties are generally highly branched to maximize the production of female flowers Footnote 205 .

In general, plants are erect with simple to well-branched stems and highly variable in height depending on genetic constitution and environmental factors, typically ranging from 0.2 to 5 meters (m) (though heights of over 12 m in cultivation are reported) Footnote 205 . Root morphology is adaptable to soil characteristics and water availability. Generally, the root is a laterally branched taproot that may penetrate up to 2.5 m deep to access sub-surface moisture. The stems are erect, furrowed, and usually branched, with a woody interior, and may be hollow in the internodes Footnote 205 .

The larger leaves (sometimes called “fan leaves”) are compound with an odd number (3 to 13) of leaflets that radiate from a single point at the distal end of each petiole. The leaflets are lanceolate or occasionally ovoid or oblanceolate, with serrate (rarely doubly serrate) margins. The petioles are 2 to 7 centimeters (cm) in length, arranged in opposite pairs on the lower stem and alternately near the stem apex. C. sativa can have anthocyanin-streaked foliage and stems; plants can become increasingly purple following frost Footnote 205 .

During the vegetative growth stage, male and female plants are not reliably distinguishable based on appearance. Sexually mature male and female plants are readily distinguishable; male plants typically appear less robust and taller, with more slender stems, smaller leaves, and less branching of the vegetative shoot than female plants Footnote 199 .

Flowers are imperfect (either staminate or pistillate), small, numerous, and congested in the inflorescences, with male and female flowers occurring almost invariably on different plants in the wild, but with both kinds on some modern hemp cultivars Footnote 169 Footnote 205 . Staminate flowers are produced in monoecious plants before the pistillate flowers, with occasional hermaphroditic flowers Footnote 205 . For more information on floral and seed morphology, see section 4.1.

While selected traits in domesticated varieties become genetically fixed through continued selection, environmental conditions may impact morphology. For instance, planting density can influence branching, with high-density plantings resulting in taller, slender-stemmed plants with reduced branching ideally suited for maximizing fibre production in hemp. Conversely, low-density plantings result in less competition and more branching to maximize foliage and flowers containing cannabinoids for drug-type C. sativa production Footnote 199 . Nutrient deficiency (especially nitrogen), low-light conditions, and drought can contribute to poor growth and stunted plants.

3 Geographical distribution

3.1 Origin and history of introduction

C. sativa is one of the oldest domesticated species, being cultivated since antiquity for end uses including fibre, hempseed, and for its psychotropic phytochemicals. There is uncertainty where C. sativa was domesticated and whether there are multiple centres of origin. The extensive use and spread by humans of C. sativa in the last 6,000 years have made it difficult to distinguish between wild, native populations and escapes from cultivation Footnote 25 Footnote 52 . Many areas have been proposed as the centre of origin for C. sativa, including countries in Asia and Europe Footnote 64 Footnote 138 Footnote 191 Footnote 226 .

It has been postulated that hemp plants and drug-type plants were historically selected in different geographic centres. In Europe and northern Asia, C. sativa was cultivated almost exclusively for its fibres, while in southern Asia, it was used as a drug for recreational, cultural, and spiritual purposes Footnote 199 . Thus, there was a north-south separation of C. sativa forms grown mostly for fibre and those grown mostly for drug uses. Northern fibre-type germplasms are adapted to the relatively short growing seasons of such latitudes. Hemp was sequentially introduced to western Asia, Egypt, and Europe between approximately 1,000 and 2,000 Before the Common Era (BCE) Footnote 200 . Drug-type C. sativa germplasms are conversely adapted to southern latitudes experiencing little seasonal changes in photoperiod. Certain forms of drug-type C. sativa flower comparatively earlier, which has been hypothesized to be an adaptation to a shorter growing season imposed by seasonal drought conditions occurring in southwestern Asia Footnote 199 . The varieties from which present C. sativa strains originated have become rare because of widespread crossbreeding Footnote 139 . For a detailed discussion of these historically selected groups of C. sativa, see Chapter 18 of Ernest Small’s monograph on Cannabis Footnote 199 .

3.2 Native range

C. sativa is widely believed to have originated in temperate, central or western Asia and perhaps eastern Asia Footnote 125 Footnote 138 Footnote 199 .

3.3 Introduced range

C. sativa is a globally cultivated and introduced species occurring in North and South America, Europe, Africa, Asia, and Australasia Footnote 14 Footnote 21 . C. sativa is widely present in North America and as of July 2019 was listed as introduced in all Canadian provinces except Newfoundland and Prince Edward Island Footnote 43 , though other sources have reported it in all provinces Footnote 61 Footnote 205 . Most wild populations occur where hemp was historically cultivated, and in Canada, it is well established along the St. Lawrence River and lower Great Lakes regions of Ontario and Quebec Footnote 61 Footnote 205 . In the United States, the naturalized range includes the Midwest and Northeast where hemp was historically cultivated Footnote 13 Footnote 205 .

Wild-growing hemp populations are frequent in Eurasia, particularly in southeast and central Asia and many European countries. To a lesser extent, wild-growing populations are found in South America and Australia Footnote 199 . C. sativa is generally said to be adapted to a northern-temperate climate and seldom escapes cultivation in tropical areas Footnote 199 .

3.4 Potential range in North America

The current known distribution of outdoor production of C. sativa across the globe suggests that its potential global range comprises zone 4 through zone 13 of the global plant hardiness zone map Footnote 128 . C. sativa growth and development in zones 10 and 11 is conditional on adequate precipitations in those areas. Naturalized C. sativa is rare south of 37° degrees north latitude, uncommon in the western United States, and very rare in Mexico Footnote 205 . Domesticated C. sativa tolerates heat well but not cold, with optimal growing temperature between 14 degrees Celsius (°C) and 27°C Footnote 205 . C. sativa may tolerate light frosts (-6°C) but is killed by heavy frosts or extended periods of near-freezing temperature Footnote 205 . Canada’s short growing season may prevent seed maturation and limit the establishment of C. sativa. However, C. sativa may adapt to the shorter photoperiods and cooler temperatures. With the recent increase of legal cultivation of both hemp and drug-type C. sativa in Canada, at least some expansion of the range of plants growing without human care is inevitable (E. Small, personal communication, 2019).

3.5 Habitat

Cultivated drug-type C. sativa and hemp can be grown in outdoor fields, greenhouses, or indoor environments. Wild C. sativa is a nitrophile and grows vigorously in moist but well-drained, well-manured, open and sunny locations situated close to water. C. sativa requires a moist climate or abundant soil moisture for growth, and is highly sensitive to light (that is, for cannabinoid production) Footnote 72 . Plants grow optimally in fertile, sandy-loam soils but will also grow in very sandy soils. In nutrient-deficient soils, especially those low in nitrogen, plants are stunted. Heavy, water-holding clay soils are unsuitable due to the intolerance of C. sativa to waterlogged conditions Footnote 199 . In Eurasia, wild C. sativa has been observed on the edges of cultivated fields, in ravines, hollows, sunny patches in woodland valleys, and on rubbish heaps near settlements or habitation Footnote 72 Footnote 205 . In North America, wild C. sativa tends to grow in well-manured, moist farmyards, and in open habitats, waste places (roadsides, railways, vacant lots), occasionally in fallow fields, and open woods Footnote 13 . C. sativa is generally poorly adapted for penetrating established stands of perennial vegetation; conversely, it is well adapted to sites with recent soil disturbances Footnote 199 .

4 Biology

4.1 Reproductive biology

C. sativa reproduces exclusively by seed and does not naturally reproduce vegetatively Footnote 205 . The life cycle of C. sativa usually takes 4 to 6 months to complete Footnote 54 ; this may be shortened to about 2 months in northern adapted C. sativa or under specific environmental conditions Footnote 129 . C. sativa is a wind-pollinated species; wind can carry pollen long distances. Pollen production lasts approximately 3 weeks, but this varies greatly based on the genotype and sowing date Footnote 27 Footnote 201 .

Wild plants, traditional hemp cultivars and landraces, and drug biotypes are dioecious. Dioecious plants are mostly or entirely cross-pollinated; male C. sativa plants tend to flower 1 to 3 weeks before female plants, therefore favouring outcrossing Footnote 197 . Many recent fibre and oilseed cultivars are monoecious (containing both male and female reproductive organs). Male flowers on monoecious plants typically appear on the distal part of the plant and are produced before female flowers, which are located on the basal parts of the plant Footnote 197 Monoecious plants can self-pollinate to some degree (20 to 25%) Footnote 199 .

Sex development in C. sativa is modifiable by environmental factors and hormonal applications Footnote 110 . Once flowers have differentiated, they will not change, but subsequent flowers on the same plant may develop into the opposite sex. For example, application of auxins or ethylene feminizes C. sativa plants Footnote 108 Footnote 147 whereas gibberellins have been reported to masculinize them Footnote 29 Footnote 48 . Additionally, when C. sativa plants were subjected to ultraviolet light and modified day-length duration the proportion of female and male plants adjusted; female plants increased after seed exposure to ultraviolet light or carbon monoxide and decreased in response to shorter day-length and higher nitrogen levels in the root zone Footnote 104 Footnote 109 .

The initiation of some floral primordia may occur after the main period of vegetative growth, but the production of most flowers is induced in most strains by consecutive days with short photoperiods. For most drug-type C. sativa plants, flowering is triggered when the minimum uninterrupted period of darkness is increased to 10 to 12 hours for some weeks Footnote 54 Footnote 197 . Some biotypes (a group of organisms with the same genetic constitution), especially those from the northernmost and southernmost extremes, are photoperiod insensitive (“autoflowering”). Many biotypes that normally require short-day photoperiodic induction to flower will eventually flower under continuous light Footnote 37 Footnote 110 .

Female flowers are developed in simple inflorescences known as racemes and are present in dense clusters (compound racemes). Female flowers possess a “perigonal bract” that arises under each flower and grows to envelop the fruit. These bracts have the highest density of glandular trichomes – tiny secretory resin glands that produce and accumulate cannabinoids (that is, tetrahydrocanabolic acid [THCA], cannabidiolic acid [CBDA]), and terpenes (that is, monoterpenes and sesquiterpenes) Footnote 126 . The number of glandular trichomes varies amongst individual plants. On female flowers, 3 types of glandular trichomes have been identified based upon their morphology: bulbous, sessile, and stalked Footnote 100 . Bulbous trichomes are the smallest and produce limited specialized metabolites. The 2 main glandular trichome types, sessile and stalked, are similar architecturally; both have a globose head and sit above the epidermal surface by a multicellular stalk Footnote 101 Footnote 126 . The main differences between the 2 types are that stalked trichomes have higher THC concentrations, are larger, and are more abundant. Other young aerial tissues also contain a relatively high concentration of these epidermal secretory glands (albeit substantially less than the perigonal bracts), suggesting a protective function Footnote 199 .

Individual male flowers are short-stalked, drooping, and arranged in larger, loose, determinate inflorescences Footnote 171 . The flowers appear in pairs, usually on special floral branches but they can also be found at the bases of some vegetative branches. Male flowers are greenish or whitish with five petals and prominent stamens, are small in size, extend on short pedicels Footnote 13 Footnote 199 and bear glandular trichomes on their anthers and filaments Footnote 203 . Male flowers produce small, light, and dry pollen grains in large quantities Footnote 79 Footnote 169 and are highly-attractive to pollen-collecting bees and flies. Male plants shed pollen and die several weeks before seed ripening on female plants of the same population Footnote 54 Footnote 169 , while female plants continue to grow as seeds develop. The single achene (fruit, commonly called a seed) in each female flower ripens in 3 to 8 weeks Footnote 54 .

The seeds of C. sativa are ovoid, small ( generally 2 to 5 mm long), and protected by the perianth. They are generally brown or grey in cultivated forms, whereas wild C. sativa seeds are covered by a darkly coloured and mottled perianth Footnote 199 . The seeds of wild C. sativa plants are smaller and lighter than those of domesticated plants, usually less than 3.8 mm in length. Some cultivated domestic plants have 15 seeds in a gram, whereas some wild plants have over 1000 seeds in a gram Footnote 197 . Wild seeds have an elongated and narrowing base and a well-developed abscission zone, which promotes easy seed shattering upon ripening (seeds readily disarticulate from the pedicel) Footnote 149 Footnote 231 . Wild C. sativa seeds mature sequentially on each plant, so that the seeds are dispersed at different times and do not interfere with each other’s ability to fall off the plant Footnote 149 Footnote 199 . Seeds of wild C. sativa exhibit long-term dormancy and irregular germination, and usually exhibit lower germination than domesticated seeds.

4.2 Cannabis sativa biochemistry

The C. sativa plant synthesizes over 100 terpenophenolic secondary metabolites known as cannabinoids Footnote 65 Footnote 76 Footnote 77 Footnote 97 Footnote 167 . C. sativa synthesizes about 140 terpenoids (hydrocarbon terpenes and their oxygenated derivatives); however, none is unique to Cannabis Footnote 41 Footnote 140 Footnote 182 Footnote 187 . C. sativa is valued for the psychoactive and potential pharmacological properties of cannabinoids, whereas certain terpene (monoterpene and sesquiterpene) components are responsible for much of the aroma and flavour. Cannabinoids and terpenes are found in resin synthesized in secretory cells inside the glandular trichome heads pyrophosphate Footnote 116 Footnote 156 . Cannabinoid and terpenoid biosynthetic pathways partially overlap in their initial step with the synthesis of the common precursor geranyl pyrophosphate Footnote 36 Footnote 185 .

4.2.1 Cannabinoids

In living plants of C. sativa and freshly harvested tissues, the cannabinoids exist predominantly in the form of carboxylic acids; for example, THC occurs as tetrahydrocannabinolic acid (THCA), and CBD occurs as cannabidiolic acid (CBDA). Non-enzymatic decarboxylation of the cannabinoids into their neutral counterparts occurs relatively slowly with aging, and catalyzed by heat, light, or alkaline conditions. cannabinoids are formed through decarboxylation of their respective 2-carboxylic acids (2-COOH), a process that is catalyzed by heat, light, or alkaline conditions Footnote 82 Footnote 216 .

Cannabinoids have been subdivided into 10 subclasses Cannabis Footnote 41 Footnote 75 Footnote 179 Footnote 218 (for molecular structures see Brenneisen, 2007 Footnote 41 , p. 17-41):

  1. Cannabigerol (CBG) type: CBG was the first cannabinoid identified Footnote 85 . Other cannabinoids of this group are the CBG precursor cannabigerolic acid (CBGA), the propyl side-chain analogs and a monomethyl ether derivative. CBG is the first cannabinoid synthesized in the plant’s cannabinoid synthesis pathway. It is the precursor of Δ 9 -tetrahydrocannabinolic, cannabidiolic, and cannabichromenic acids, and normally appears in the plant at relatively low concentration because the majority is further metabolized to end products, except in specifically bred strains Footnote 66Footnote 213 .
  2. Cannabichromene (CBC) type: To date, 5 CBC-type cannabinoids, mainly present as C5-analogs, have been identified. Its production is normally maximal at the earlier growth stages of the plant Footnote 67 .
  3. Cannabidiol (CBD) type: 7 CBD-type cannabinoids with C1 to C5 side chains have been characterized. CBD and its corresponding acid, CBDA, are the predominant cannabinoids in industrial hemp. It should be noted that genes encoding the CBD and THC synthases are co-dominant such that one is expressed at the expense of the other Footnote 223 .
  4. Δ 9 -Tetrahydrocannabinol (THC) type: 9 THC-type cannabinoids with C1 to C5 side chains have been identified. THC acid A (THCA-A) and B (THCA-B) are the 2 biogenic precursors of THC, although THCA-B is present to a much lesser extent. THC is the main psychotropic principle; the acids are not psychoactive. Female C. sativa plants have up to 20 times the concentration of THC in comparison to male plants. When females are grown in the absence of males, higher concentrations of THC are produced in their reproductive parts Footnote 203 .
  5. Δ 8 -THC type: Δ 8 -THC and its acid counterpart, Δ 8 -THCA, are considered as THC and THCA artifacts, respectively. The activity of Δ 8 -THC is estimated 20% lower than THC’s Footnote 41 .
  6. Cannabicyclol (CBL) type: This group comprises CBL, its acid precursor, and the C3 side-chain analog. These three cannabinoids are characterized by a five-atom ring and C1-bridge instead of the typical ring A. CBL is known to be a heat-generated artifact from CBC Footnote 41 .
  7. Cannabielsoin (CBE) type: This group includes CBE and its acid precursors A and B, and they are artifacts formed from CBD Footnote 41 .
  8. Cannabinol (CBN) and Cannabinodiol (CBND) types: This subclass comprises 6 CBN- and 2 CBND-type cannabinoids which are oxidation artifacts of THC and CBD, respectively Footnote 41 .
  9. Cannabitriol (CBT) type: 9 CBT-type cannabinoids have been described and they are characterized by additional hydroxy group substitution Footnote 41 .
  10. Miscellaneous types: 11 cannabinoids with unusual structures such as furano ring (dehydrocannabifuran, cannabifuran), carbonyl function (cannabichromanon, 10-oxo-δ-6a-tetrahydrocannabinol), or tetrahydroxy substitution (cannabiripsol), have been identified Footnote 41 .

Pharmaceutical properties and medicinal uses of cannabinoids are described in the scientific literature, for details see Russo Footnote 184 Footnote 185 , Pertwee Footnote 163 , Whiting et al. Footnote 229 , CCSA Footnote 7 , Grotenhermen and Müller-Vahl Footnote 96 , Russo and Marcu Footnote 187 , Urits et al. Footnote 222 , among others.

4.2.2 Terpenoids

The characteristic odor of Cannabis plants can be attributed to a mixture of volatile compounds, including monoterpenes, sesquiterpenes, and other terpenoid-like compounds Footnote 199 . C. sativa terpenoids include, but are not limited to, α-pinene, limonene, β-myrcene, D-linalool, caryophyllene oxide and β-caryophyllene which is typically the most common of all terpenoids in C. sativa Footnote 140 and predominates quantitatively in C. sativa extracts Footnote 99 . The proportion of monoterpenes (such as limonene, myrcene, pinene) in the plant is typically greater than that of sesquiterpenes Footnote 113 , but monoterpenes volatilize readily during curing, drying, and storage resulting in a higher relative proportion of sesquiterpenes such as caryophyllene Footnote 180 Footnote 218 . The particular mixture of mono- and sesquiterpenoids determines the viscosity of the resinous content of the trichomes Footnote 185 . Trichome exudate can trap insects Footnote 137 and the phenomenon is illustrated by Small (2017, p. 219) Footnote 200 .

Pharmaceutical properties and medicinal uses of terpenoids are described in the scientific literature, for further details see Russo Footnote 185 Footnote 186 and Russo and Marcu Footnote 187 .

4.2.3 Biosynthesis of terpenoids and cannabinoids

Terpene synthesis in plants involves 2 compartmentalized pathways: the plastidial methylerythritol phosphate (MEP) pathway, and the cytosolic mevalonate (MEV) pathway Footnote 36 . Both biosynthetic pathways lead to the production of substrates that ultimately serve as precursors for not only terpene synthesis but also cannabinoid synthesis (for further details, see Russo Footnote 185 ; Andre et al. Footnote 28 ; Booth et al. Footnote 36 ).

The biosynthetic pathway producing the major cannabinoids with pentyl side chains (CBCA, CBDA, CBGA, and THCA) is now fully elucidated, with CBCA and THCA being described lately. For more details on cannabinoid biosynthesis see Taura et al. Footnote 214 Footnote 215 , Sirikantaramas et al. Footnote 192 , Flores-Sanchez and Verpoorte Footnote 83 , Russo Footnote 185 , van Bakel et al. Footnote 223 , Gagne et al. Footnote 84 , Stout et al. Footnote 208 , Andre et al. Footnote 28 , and Laverty et al. Footnote 122 . Most of the minor cannabinoids, including those with propyl side chains, likely are produced by fatty acids with varying chain-lengths being fed into the “core” cannabinoid pathway.

Several factors influence the amount and quality of the cannabinoids produced in any given C. sativa plant including, the genotype and plant organs, the growth stage, environmental factors, stressors, and polyploidization.

    Genotype and plant organs

The concentration of cannabinoids and terpenoids varies between plant tissues Footnote 200 and among cultivars or biotypes Footnote 35 Footnote 168 depending on the genetic background of the plant. In general, in any given C. sativa plant, the cannabinoid concentration increases in the following order: roots, large stems, smaller stems, older and larger leaves, younger and smaller leaves, and perigonal bracts covering the female flowers Footnote 200 . The density of resin-containing glandular trichomes, the size of the trichome heads, and biosynthetic efficacy considerations determine the amount of THC, cannabinoids and terpenes synthesized Footnote 199 .

Cannabinoid content in the plant generally increases from the seedling stage to the flowering stage because the glandular trichomes that synthesize cannabinoids are concentrated in the reproductive-stage leaves on the female inflorescence Footnote 107 Footnote 120 Footnote 121 Footnote 165 Footnote 196 Footnote 219 . Seedless drug-type female inflorescences are obtained by eliminating male plants from the growing area, which results in increased concentrations of THC, other cannabinoids, and terpenoids Footnote 54 , largely because seeds, if allowed to develop, are a diluent and a drain on the plant’s carbon allocation to specialized metabolism. Most drug type C. sativa is produced today from female clones that are reproduced using cuttings and rarely produce seed Footnote 45 .

See also  Marijuana seed to sale tracking

Soil, atmospheric, climatic, and management factors that contribute to vigorous growth and development of plants can increase the absolute production of resin and THC in drug-type C. sativa. Such factors include soil fertility, light, heat, and carbon dioxide (CO2) Footnote 199 .

C. sativa hemp plants subject to abiotic stressors such as nutrient deficiencies or drought tend to produce more THC per unit of biomass Footnote 103 Footnote 148 Footnote 195 .

Polyploidization has been found to have varying effects in terms of cannabinoid and terpenoid production in hemp and drug-type C. sativa. For more detail on this relationship see De Pasquale et al. Footnote 69 , Clarke Footnote 51 , Bagheri and Mansouri Footnote 31 , Mansouri and Bagheri Footnote 130 , and Parsons et al. Footnote 161 . A polyploid form of drug-type C. sativa has not been commercialized.

4.3 Breeding and seed production

4.3.1 Breeding for cannabinoid content

The genetics and underlying biochemistry that regulates the overall ratio of the 4 major cannabinoids are now well known. The upstream portion of the cannabinoid biosynthetic pathway produces CBGA, a common substrate for the enzymes that produce CBDA, THCA, and CBCA. Thus, the overall cannabinoid ratio is dependent on the individual activities of these enzymes, which in turn is dependent on the genetic makeup of the individual plant. In general, most individual C. sativa plants are either CBDA-dominant or THCA-dominant, with the remainder of the major cannabinoids constituting a smaller percentage of the overall cannabinoid content. There are rare instances of genotypes that are dominant for CBCA or CBGA. The alleles that encode the enzymes THCA synthase and CBDA synthase are co-dominant, and thus crossing a CBDA-dominant plant with a THCA-dominant plant produces progeny with equal proportions of these cannabinoids Footnote 28 .

Throughout the ages, hemp largely has been bred for seed and fibre quality. In general, all industrial hemp produced today is CBDA-dominant with low total cannabinoid content compared to drug-type C. sativa Footnote 188 . Regulatory bodies use the proportion of cannabinoids to differentiate drug-type C. sativa and industrial hemp. The upper concentration limit for THCA+THC content in industrial hemp was proposed as 0.3% (dry weight) by Small and Cronquist (1976) Footnote 202 . This threshold is used in Canada and the United States, while the European Union uses a threshold of 0.2% Footnote 200 . In some industrial hemp varieties, there can be individual plants found that are THCA-dominant or THCA/CBDA equal, which may account for why some hemp varieties more commonly fail the THC content criterion when randomly sampled (J. Stout, personal communication, 2020). Breeders could lower THC levels by targeting cannabinoid biosynthetic pathways or by disrupting the morphogenesis of cannabhen randomly sampled (J. Stout, personal communication Footnote 68 .

One of the main breeding objectives for drug-type C. sativa is to increase total cannabinoid content while maintaining THCA-dominance. Some commercial strains of drug-type C. sativa reportedly contain up to 21% THCA in dried female flowers Footnote 35 . Biotechnology companies have developed strains that predominantly produce 1 of the 4 major cannabinoid compounds (THCA, CBDA, CBCA, and CBGA), as well as strains with mixed cannabinoid or terpenoid profiles Footnote 52 . Several commercial drug-type C. sativa strains have been described by Rosenthal Footnote 175 – Footnote 178 , Snoeijer Footnote 206 , Danko Footnote 60 , Grisswell and Young Footnote 95 , Oner Footnote 150 Footnote 151 Footnote 152 Footnote 153 Footnote 154 Footnote 155 , and Backes Footnote 30 . However, while numerous strains have been named, not all reflect unique biotypes largely due to the undocumented nature of drug-type C. sativa breeding programs Footnote 188 . Strain names are not accepted as cultivars under the International Code of Nomenclature for Cultivated Plants Footnote 42 .

4.3.2 Seed production

Varietal purity standards for pedigreed seed production of both registered and certified industrial hemp seed have been developed by the Canadian Seed Growers’ Association Footnote 11 .

4.4 Cultivation and use as crop

C. sativa is used for its fibre, oil (for vegetable oil and oilseed products), and recreational or medicinal drug purposes Footnote 204 . Claimed pharmacological properties attributed to Cannabis are discussed by Russo Footnote 185 Footnote 186 , Whiting et al. Footnote 229 , CCSA Footnote 7 , and Russo and Marcu Footnote 187 , among others. Hemp is universally cultivated as a field crop for its uses as oil, biomass, or both, while legal drug-type C. sativa is cultivated mostly indoors or in greenhouses, with low acreage in outdoor fields Footnote 28 . In Canada, the majority of hemp is grown for seed production Footnote 105 .

Commercial cultivation of industrial hemp in Canada falls under the Industrial Hemp Regulation and the associated requirements from obtaining and maintaining a licence from Health Canada. Only varieties named in the “List of Approved Cultivars”, published by Health Canada, are approved for planting in Canada.

The Cannabis Act and its regulations came into force on October 17, 2018 . The Cannabis Act and its regulations provide the framework for the legal production of drug-type C. sativa. Commercial cultivators of drug-type C. sativa (not for personal use) are required to obtain a licence from Health Canada Footnote 16 Footnote 17 . Applicants may apply under the subclasses of micro-cultivation, standard cultivation, or nursery cultivation.

Crop guides for the cultivation of industrial hemp have been published by several provincial agriculture departments – Alberta Footnote 1 , Manitoba Footnote 18 , Ontario Footnote 19 , Saskatchewan Footnote 22 and the Canadian Hemp Trade Alliance Footnote 10 . Many guides pertaining primarily to the non-commercial cultivation of drug-type C. sativa have been published, including Clarke Footnote 50 , Rosenthal Footnote 174 Footnote 175 Footnote 176 Footnote 177 Footnote 178 , Green Footnote 93 , and Cervantes Footnote 47 .

Vegetative propagation by cuttings and tissue culture techniques are widely practiced in drug-type C. sativa production systems to preserve a known genetic or biochemical profile Footnote 199 Footnote 221 .

4.5 Gene flow during commercial production

C. sativa is a naturally outcrossing species, with rare instances of self-fertilization. In dioecious varieties, a single male flower can produce 350,000 pollen grains and a single plant contains many male flowers Footnote 201 . C. sativa is wind-pollinated. Small and Antle Footnote 201 (2003) measured hemp pollen dispersal and found pollen density fell to less than 1% of the density within the field at 100 m, but the decrease measured at 400 m was proportionally less. Pollen dispersal of over 300 kilometers (km) Footnote 205 and even between North Africa and southwestern Europe has been reported Cabezudo et al. Footnote 44 . C. sativa pollen can remain viable for days, if not over a week under optimal conditions Footnote 33 Footnote 201 . Intraspecific gene flow between industrial hemp and drug type lines cultivated in the field is a growing concern.

In Canada, isolation distances of up to 4.8 km are required for pedigreed industrial hemp seed production Footnote 11 .

4.6 Cannabis sativa as a potential weed of agriculture

C. sativa plants tolerate a wide range of conditions, have high genetic variability, and are adaptable to environmental conditions; these characteristics could increase weediness and the colonization of new locations Footnote 72 . Hemp has been documented to grow as a weed in Footnote 102 Footnote 103 Footnote 197 .

  • field margins
  • farmyards
  • waste places
  • on rubbish heaps near habitations
  • open lots
  • in pasturelands
  • fallow fields
  • along or beside roadsides
  • railways
  • ditches
  • creeks
  • fence rows
  • bridge embankments
  • lowland drainage tributaries
  • open woodlands

Hemp, as a weed, has been documented in southeast and central Asia, Europe, South America, Australia, and Africa Footnote 63 . In North America, hemp has naturalized where its cultivation was concentrated historically in the U.S. midwest and southeast, southern Ontario, and southern Quebec. C. sativa has been reported growing outside of agricultural systems in Canadian provinces from British Columbia to New Brunswick Footnote 194 Footnote 205 . Small et al. Footnote 205 observed hemp volunteers 4 years after the completion of a hemp trial in Ottawa, Canada.

Despite the historical prohibition of drug-type C. sativa production in Canada, insight on its weediness can be gained from the behaviour of hemp in areas where production has been authorized. Hemp has weedy tendencies, as indicated by Small Footnote 195 ; hemp biotypes have been capable of escaping cultivation and adapting very well to growing without human intervention in about 50 generations. However, it is unlikely that drug-type C. sativa would display increased weediness compared to hemp. Throughout centuries of selection, the phenotypes of drug-type C. sativa and hemp have diverged, notably the plant architecture. The short stature of most drug-type C. sativa plants grown in Canada (in contrast to fibre-type C. sativa) minimizes the production of stem tissues while maximizing the production of floral tissues Footnote 205 . Minimizing harvest losses will reduce C. sativa volunteers in subsequent crops. Cold temperatures and short photoperiods would negatively impact the ability of C. sativa, especially types adapted to indoor cultivation and semi-tropical climates, to produce seeds before fall and thus, establish as a weed Footnote 205 .

Many broadleaf herbicides will control volunteer C. sativa. Pre-plant or pre-emergent burndown using 2,4-D or glyphosate will generally control hemp in the spring Footnote 205 . Mechanical control, followed by chemical control the following year, is recommended for mature plants Footnote 205 .

4.7 Means of movement and dispersal

Humans, birds, and water are the primary dispersal agents of C. sativa seeds. C. sativa seeds are highly attractive to birds, hence the opinion of Haney and Bazzaz Footnote 102 that birds were the most important wild animals for disseminating seeds in North America. Some C. sativa seeds can survive the digestive tract of birds Footnote 62 , while others may adhere to claws or bills Footnote 141 . Flood and runoff waters may also disperse seeds Footnote 102 .

5 Related species of Cannabis sativa L.

5.1 Inter-species/genus hybridization

The Cannabaceae family, as currently described, comprises about 102 accepted species and 12 genera including Footnote 24 :

  • Aphananthe (4 spp.)
  • Cannabis (1 sp.)
  • Celtis L. (72 spp.)
  • Gironniera (6 spp.)
  • Humulus (3 spp.)
  • Lozanella (2 spp.)
  • Pteroceltis (1 sp.)
  • Trema (13-spp.)

Cannabis and Humulus (hop) are phylogenetically close Footnote 230 . However, there is no reliable evidence reported in the literature of sexual hybridization between C. sativa and the 3 species of the genus Humulus (H. lupulus (common hop), H. japonicus, and H. yunnanensis).

5.2 Potential for introgression of genetic information from Cannabis sativa into relatives

In Canada, there are no relatives known to interbreed with C. sativa. Thus, the risk of interspecific gene flow is low Footnote 45 . Introgression of genetic information from C. sativa will be restricted to other C. sativa plants. All taxa within the species C. sativa readily crossbreed, often by way of long-distance pollination (see Section 4.5 Gene flow during commercial production).

6 Potential interaction of Cannabis sativa with other life forms

C. sativa plants display mechanical and chemical defense mechanisms including the occurrence of cystolith trichomes, resinous exudate from glandular trichomes, and emission of volatile terpenoids Footnote 162 . Upper surfaces of C. sativa leaves are covered by abrasive cystolith trichomes (that is, unicellular hairs that have particles of calcium carbonate in their base). Cystolith trichomes impart a roughness to the surface of leaves that can cause skin irritation or dermatitis in people handling C. sativa and may discourage herbivory by larger animals Footnote 199 ; they also may impale small insects and damage the mouthparts of larger ones Footnote 124 . C. sativa leaves and floral parts are also covered by glandular trichomes which secrete many organic compounds including terpenoids and cannabinoids. Glandular trichomes may rupture and release a viscous mixture that can trap insects, as illustrated by Small (2017, p. 219) Footnote 200 and described by McPartland and colleagues Footnote 137 , or be unpalatable to herbivores.

Several volatile terpenes produced by C. sativa including limonene, pinene, humulene, and caryophyllene have insecticidal properties Footnote 137 Footnote 142 and are synthesized and accumulated in trichomes Footnote 98 . Although the biosynthesis of terpenoids with insecticidal properties occurs across all forms of C. sativa, drug-type C. sativa produces 3 to 6 times more resinous components, including limonene and pinene, than most hemp varieties Footnote 140 . Cannabinoids such as THC and THCA also possess insecticidal properties Footnote 134 Footnote 137 Footnote 181 Footnote 183 Footnote 215 . The levels of exposure of insects to insecticidal compounds synthesized by C. sativa, such as limonene, pinene, and THC, are unknown.

Pollen-producing male C. sativa flowers are attractive to bees and pollen-collecting flies, particularly when nectar-producing species are absent Footnote 199 . The pollen of C. sativa plants was reported to contain cannabinoids and volatile terpenes Footnote 157 Footnote 182 ; however, this is likely the result of contamination from staminal trichomes as the pollen itself has no trichomes Footnote 199 . The potential impact of C. sativa pollen on bee health at the individual and colony level is unknown.

Herbivores have been known to ingest escaped C. sativa and the plant material (not the seeds) appears to have toxic potential if eaten in very large amounts. In general, C. sativa is not considered to be significantly poisonous Footnote 205 .

According to McPartland Footnote 133 , nearly 300 insect pests have been associated with C. sativa, but very few cause economic losses. Some of the most common and serious pests are mites (e.g., two-spotted mite, Tetranychus urticae, and the hemp russet mite, Aculops cannabicola), borers (such as the European corn borer, Ostrinia nubilalis, and the hemp borer, Grapholita delineana), aphids (such as Phorodon cannabis), budworms (such as Helicoverpa armigera), and beetle larvae (such as Psylliodes attenuata, Ceutorhynchus rapae, Rhinocus pericarpius, Thyestes gebleri, and several Mordellistena spp.). For more detailed information on pests of C. sativa, see McPartland Footnote 133 .

For a list of species associated with C. sativa, please refer to Table 1.

Table 1. Examples of potential interactions of Cannabis sativa with other life forms present in Canada during its life cycle.

Bacteria

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Agrobacterium spp.
(crown gall, gall)
Synonym: Rhizobium spp.
Pathogen (Bradbury, 1986 Footnote 40 )
Erwinia tracheiphila (Smith)
Bergey et al., Hauben et al.
(bacterial wilt)
Pathogen (Bradbury, 1986 Footnote 40 )
Pseudomonas syringae pvs
(mulberry blight, Wisconsin tobacco disease)
Pathogen (CABI/EPPO, 2009 Footnote 5 ; Bradbury, 1986 Footnote 40 )
Fungi

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Alternaria spp.
(blight)
Pathogen (Farr et al., 2018 Footnote 80 )
Aspergillus spp.
(stalk end rot of fruit).
Pathogen (Clear and Patrick, 1995 Footnote 56 ; Conners, 1967 Footnote 57 ; Elmhirst and Joshi, 1995 Footnote 74 ; Ginns, 1986 Footnote 91 ; Miller et al., 1985 Footnote 143 ; Mills and Abramson, 1981 Footnote 144 )
Botrytis cinerea Pers.
(gray mold)
Synonym: Botryotinia fuckeliana (deBary) Whetzel
Pathogen (Conners, 1967 Footnote 57 ; Gossen et al., 1994 Footnote 92 ; Legault et al., 1989 Footnote 123 ; Parmelee, 1983 Footnote 159 ; Rodriguez et al., 2015 Footnote 172 )
Cladosporium herbarum
(Persoon) Link
(cladosporium stem canker)
Pathogen (McPartland et al., 2000 Footnote 137 )
Colletotrichum dematium (Pers.) Grove
(leaf spot)
Synonym: Vermicularia dematium (Persoon) Fries
Pathogen (Cerkauskas et al., 1991 Footnote 46 ; Ginns, 1986 Footnote 91 )
Fusarium spp.
(canker)
Pathogen (Clear and Patrick, 1990 Footnote 55 ; Duthie et al., 1986 Footnote 71 ; Farr et al., 2018 Footnote 80 ; Martin and Johnston, 1982 Footnote 131 ; Sturz and Bernier, 1991 Footnote 209 ; Sturz and Johnston, 1983 Footnote 210 ; Wall and Shamoun, 1990 Footnote 225 )
Glomus mosseae (T.H. Nicolson & Gerd.) Gerd. & Trappe Symbiont (Dalpe et al., 1986 Footnote 59 ; Kucey and Paul, 1983 Footnote 119 ; Traquair and Berch, 1988 Footnote 217 )
Macrophomina phaseoli
(Maubl.) S.F. Ashby
(charcoal rot, damping-off)
Synonym: Macrophomina phaseolina (Tassi) Goid
Pathogen (Conners, 1967 Footnote 57 ; Desjardins et al., 2007 Footnote 70 ; Joshi and Hudgins, 2002 Footnote 114 )
Nectria haematococca Berk. & Broome
(dry rot of potato)
Synonym: Fusarium solani (Martius) Sacc.
Pathogen (Conners, 1967 Footnote 57 ; Duthie et al., 1986 Footnote 71 ; Joshi and Elmhirst, 1998 Footnote 115 ; Sturz and Bernier, 1991 Footnote 209 ; Sumar et al., 1982 Footnote 211 )
Ophiobolus anguillides (Cooke in Cooke & Ellis) Sacc.
(stem canker)
Pathogen (Conners, 1967 Footnote 57 ; Ginns, 1986 Footnote 91 )
Pythium aphanidermatum (Edson) Fitzp.
(damping-off)
Pathogen (Farr et al., 2018 Footnote 80 ; Gilbert et al., 2008 Footnote 88 )
Sclerotinia sclerotiorum (Lib.) de Bary
(hemp canker, soft rot or stem rot)
Pathogen (CABI, 2018a Footnote 2 ; Farr et al., 2018 Footnote 80 )
Sclerotium rolfsii Sacc.
(southern blight)
Synonym: Athelia rolfsii (Curzi) C. C. Tu & Kimbr.
Pathogen (Chang and Mirza, 2007 Footnote 49 )
Septoria spp.
(blight of hemp, yellow leaf spot)
Pathogen (CABI, 2018a Footnote 2 ; Conners, 1967 Footnote 57 )
Sphaerotheca macularis (Wallr.) Magnus
(powdery mildew)
Synonym: Podosphaera macularis (Wallr.) U. Braun & S. Takam.
Pathogen (Ginns, 1986 Footnote 91 ; Parmelee, 1982 Footnote 158 ; Parmelee, 1984 Footnote 160 ; Wall and Shamoun, 1990 Footnote 225 )
Trichothecium roseum
(false powdery mildew)
Pathogen (Ginns, 1986 Footnote 91 ; Mittal and Wang, 1987 Footnote 145 )
Trichothecium roseum
(false powdery mildew)
Pathogen (CABI, 2018b Footnote 3 )
Viruses

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Alfalfa mosaic virus (AMV) Pathogen (CABI/EPPO, 2002 Footnote 4 ; Conners, 1967 Footnote 57 )
Arabis mosaic virus (ArMV) Pathogen (CABI/EPPO, 2015 Footnote 6 )
Cucumber mosaic virus (CMV) Pathogen (Conners, 1967 Footnote 57 )
Phytoplasma

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Candidatus Phytoplasma asteris
(yellow disease phytoplasmas)
Pathogen (Wang et al., 1998 Footnote 227 )
Nematodes

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Heterodera spp.
(cyst nematode)
Pathogen (Ebsary, 1986 Footnote 73 )
Meloidogyne spp.
(root-knot nematode)
Pathogen (Conners, 1967 Footnote 57 ; Ebsary, 1986 Footnote 73 ; Sewell, 1977 Footnote 190 ; Tyler, 1964 Footnote 220 )
Ditylenchus dipsaci (Kühn) Filipjev
(stem nematode)
Pathogen (Creelman, 1962 Footnote 58 ; Kimpinski, 1985 Footnote 117 )
Insects and mites

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Acalymma vittatum (Fabricius) Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Acheta domesticus (Linnaeus)
(house cricket)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Adalia bipunctata (Linnaeus)
(two spotted ladybeetle)
Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Agriotes spp.
(lined click beetle, wireworm click beetle)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Agromyza reptans Fallén Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Spencer and Steyskal, 1986 Footnote 207 )
Agrotis gladiaria Morrison
(claybacked cutworm)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Aleochara bilineata Gyllenhal Beneficial organism (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Gavloski et al., 2011 Footnote 87 ; McPartland et al., 2000 Footnote 137 )
Anagrus atomus (Linnaeus)
(leafhopper egg parasitoid)
Beneficial organism (CABI, 2018d Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bostanian et al., 2012 Footnote 38 ; McPartland et al., 2000 Footnote 137 )
Anoplophora glabripennis (Motschulsky)
(Asian long-horned beetle)
Consumer (CFIA, 2016 Footnote 8 ; McPartland et al., 2000 Footnote 137 )
Aphis spp.
(black bean aphid, cotton aphid)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Apion spp. Herbst Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Arctia caja (Linnaeus)
(garden tiger moth)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Bemisia spp.
(silverleaf whitefly, tobacco whitefly)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Blattella germanica (Linnaeus)
(German cockroach)
Consumer (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Bradysia germanica spp. Winnertz
(fungus gnats)
Consumer (Gillespie and Quiring, 2012 Footnote 90 ; McPartland et al., 2000 Footnote 137 )
Camnula pellucida (Scudder)
(clearwinged grasshopper)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Ceutorhynchus spp.
(cabbage curculio, cauliflower weevil)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Chaetocnema spp.
(corn flea beetle, flea beetle)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Chelonus insularis Cresson Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Krombein et al., 1979 Footnote 118 ; McPartland et al., 2000 Footnote 137 )
Chloealtis conspersa (Harris & T.W.)
(sprinkled locust)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Chrysopa spp.
(goldeneye lacewing)
Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Garland and Kevan, 2007 Footnote 86 ; McPartland et al., 2000 Footnote 137 )
Chrysoperla spp.
(green lacewing, pearly green lacewing)
Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Garland and Kevan, 2007 Footnote 86 ; McPartland et al., 2000 Footnote 137 )
Closterotomus norvegicus (Gmelin)
(strawberry bug, potato bug)
Synonym: Calocoris norvegicus (Gmelin)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Cnephasia asseclana (Denis & Schiffermüller)
(chrysanthemum web worm)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Coccinella undecimpunctata Linnaeus
(eleven-spotted ladybeetle)
Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Cotesia marginiventris (Cresson) Beneficial organism (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Philip, 2015 Footnote 164 )
Cyrtepistomus castaneus (Roelofs)
(asiatic oak weevil)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Delia spp.
(bean seed fly, cabbage maggot, seedcorn maggot)
Consumer (CABI, 2018 Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 )
Delphastus pusillus (LeConte)
(whitefly predatory beetle)
Beneficial organism (CABI, 2018 Footnote 2 ; Bousquet et al., 2013 Footnote 39 ; CFIA, undated Footnote 9 ; McPartland et al., 2000 Footnote 137 )
Deraeocoris brevis (Uhler)
(Mirid plant bug)
Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Empoasca spp.
(potato leafhopper)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Encarsia formosa Gahan
(greenhouse whitefly parasitoid)
Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; PMC, 2014 Footnote 20 ; McPartland et al., 2000 Footnote 137 )
Feltiella acarisuga (Vallot)
(red spider mite predatory gall midge)
Synonym: Therodiplosis persicae
Beneficial organism (CFIA, undated Footnote 9 ; Footnote 20 ; McPartland et al., 2000 Footnote 137 ; Mo and Liu, 2007 Footnote 146 )
Forficula auricularia Linnaeus
(European earwig)
Consumer (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Frankliniella occidentalis (Pergande)
(western flower thrips)
Consumer (CABI, 2018a Footnote 2 ; Hemming, 2000 Footnote 106 ; McPartland et al., 2000 Footnote 137 )
Graphocephala coccinea (Forster)
(redbanded leafhopper)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Grapholita delineana (Walker) Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Harmonia axyridis Pallas
(multicolored Asian ladybeetle)
Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Helicoverpa zea (Boddie)
(bollworm)
Consumer (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Heliothrips haemorrhoidalis ( Bouché )
(greenhouse thrips)
Consumer (Hemming, 2000 Footnote 106 ; McPartland et al., 2000 Footnote 137 )
Hippodamia convergens Guérin-Meneville
(ladybird)
Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Liriomyza eupatorii (Kaltenbach) Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Lonsdale, 2017 Footnote 127 ; McPartland et al., 2000 Footnote 137 )
Lixophaga variablis (Coquillett) Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Tachinidae resources, 2017 Footnote 212 )
Loxostege sticticalis (Linnaeus)
(beet webworm)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Lygus lineolaris ( Palisot de Beauvois )
(tarnished plant bug)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Macrocentrus spp. Beneficial organism (CABI, 2018a Footnote 2 ; Krombein et al., 1979 Footnote 118 ; McPartland et al., 2000 Footnote 137 )
Mamestra configurata Walker
(bertha armyworm)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Melanoplus bivittatus (Say)
(two-striped grasshopper)
Consumer (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Myzus persicae (Sulzer)
(green peach aphid)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Nabis spp. Latreille Beneficial organism (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Neocrepidodera ferruginea (Scopoli)
(European rusted flea beetle)
Synonym: Crepidodera ferruginea
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Oecanthus celerinictus Walker & T.J. Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 )
Orius spp. Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Ostrinia nubilalis (Hübner)
(European corn borer)
Consumer (McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Oulema melanopus (Linnaeus)
(oat leaf beetle)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Papaipema spp.
(burdock borer, common stalk borer)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Pohl et al., 2018 Footnote 166 )
Parthenolecanium corni ( Bouché )
(European fruit lecanium)
Consumer (CABI, 2018a Footnote 2 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Peristenus digoneutis Loan Beneficial organism (CABI, 2018a Footnote 2 ; McPartland et al., 2000 Footnote 137 ; Whistlecraft et al., 2010 Footnote 228 )
Philaenus spumarius (Linnaeus)
(meadow froghopper, spittlebug)
Consumer (CABI, 2018a Footnote 2 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Phorodon humuli (Schrank)
(hops aphid)
Consumer (Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Podisus maculiventris (Say)
(spined soldier bug)
Beneficial organism (CFIA, undated Footnote 9 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Popillia japonica Newman
(Japaneese beetle)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Psylliodes punctulatus Melsheimer
(hops flea beetle)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Rhinoncus pericarpius (Linnaeus)
(hemp weevil)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Scambus pterophori (Ashmead) Beneficial organism (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Krombein et al., 1979 Footnote 118 ; McPartland et al., 2000 Footnote 137 )
Schizocerella pilicornis (Holmgren)
(purslane sawfly)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Krombein et al., 1979 Footnote 118 ; McPartland et al., 2000 Footnote 137 )
Sitona lineatus (Linnaeus)
(pea leaf weevil)
Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Stethorus lineatus spp. Beneficial organism (CFIA, undated Footnote 9 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Supella longipalpa (Fabricius) Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; McPartland et al., 2000 Footnote 137 ; Vickery and Kevan, 1986 Footnote 224 )
Systena spp. Chevrolat Consumer (Bousquet et al., 2013 Footnote 39 ; McPartland et al., 2000 Footnote 137 )
Thrips tabaci Lindeman
(onion (tobacco) thrips)
Consumer (CABI, 2018a Footnote 2 ; GBIF Backbone Taxonomy, 2017 Footnote 15 ; Hemming, 2000 Footnote 106 ; McPartland et al., 2000 Footnote 137 )
Tipula paludosa Meigen
(European crane fly)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Gillespie, 2001 Footnote 89 ; McPartland et al., 2000 Footnote 137 )
Trialeurodes vaporariorum (Westwood)
(greenhouse whitefly)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Maw et al., 2000 Footnote 132 ; McPartland et al., 2000 Footnote 137 )
Trichogramma spp.
(minute egg parasitoid, moth egg parasitoid)
Beneficial organism (CABI, 2018a Footnote 2 ; CFIA, undated Footnote 9 ; Krombein et al., 1979 Footnote 118 ; McPartland et al., 2000 Footnote 137 )
Tetranychus urticae Koch
(two-spotted spider mite)
Consumer (Beaulieu and Knee, 2014 Footnote 34 ; McPartland et al., 2000 Footnote 137 )
Molluscs

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Arion spp.
(black slug, brown-banded slug, chocolate slug, dark-face slug, dusky slug, forest slug, garden slug, hedgehog slug, orange-banded slug)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Barker, 2002 Footnote 32 ; Grimm et al., 2009 Footnote 94 ; Ranalli, 1999 Footnote 170 ; Rollo, 1974 Footnote 173 )
Deroceras reticulatum (Müller)
(meadow slug)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Grimm et al., 2009 Footnote 94 ; Ranalli, 1999 Footnote 170 )
Limax maximus Linnaeus
(giant garden slug)
Consumer (GBIF Backbone Taxonomy, 2017 Footnote 15 ; Grimm et al., 2009 Footnote 94 ; Ranalli, 1999 Footnote 170 )
See also  Gorilla fighter seeds
Animals

Other life forms Interaction with Cannabis sativa (pathogen; symbiont or beneficial organism; consumer; gene transfer) Reference(s)
Birds Consumer (McPartland et al., 2000 Footnote 137 )
Animal browsers (for example, deer, rabbits, rodents) Consumer (McPartland, 1996 Footnote 133 ; McPartland et al., 2000 Footnote 137 )

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See also  White rhino seeds

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Seed classification system for marijuana

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The Name of Cannabis: A Short Guide for Nonbotanists

This Open Access article is distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited.

Abstract

The genus Cannabis (Family Cannabaceae) is probably indigenous to wet habitats of Asiatic continent. The long coexistence between mankind and Cannabis led to an early domestication of the plant, which soon showed an amazing spectrum of possible utilizations, as a source of textile fibers, as well as narcotic and psychoactive compounds. Nowadays, the specie(s) belonging to the genus Cannabis are represented by myriads of cultivated varieties, often with unstable taxonomic foundations. The nomenclature of Cannabis has been the object of numerous nomenclatural treatments. Linnaeus in Species Plantarum (1753) described a single species of hemp, Cannabis sativa, whereas Lamarck (1785) proposed two species of Cannabis: C. sativa, the species largely cultivated in Western Continent, and Cannabis indica, a wild species growing in India and neighboring countries. The dilemma about the existence of the species C. indica considered distinct from C. sativa continues up to present days. Due to their prevalent economic interest, the nomenclatural treatment is particularly important as far as it concerns the cultivated varieties of Cannabis. In this context, we propose to avoid the distinction between sativa and indica, suggesting a bimodal approach: when a cultivar has been correctly established. It could be advisable to apply a nomenclature system based on the International Code of Nomenclature for Cultivated Plants (ICNCP): it is not necessary to use the species epithets, sativa or indica, and a combination of the genus name and a cultivar epithet in any language and bounded by single quotation marks define an exclusive name for each Cannabis cultivar. In contrast, Cannabis varieties named with vernacular names by medical patients and recreational users, and lacking an adequate description as required by ICNCP, should be named as Cannabis strain, followed by their popularized name and without single quotation marks, having in mind that their names have no taxonomical validity.

Introduction

Depending on the taxonomical treatment adopted, 1 the genus Cannabis (Hemp, Family Cannabaceae) includes up to three species, each with a very long history of domestication. Plants belonging to this genus are probably indigenous to the Asiatic Continent, where they preferably grew in wet places and near water bodies. 2 This kind of environment was also frequently chosen as a temporary settlement by human nomadic groups, before the discovery and diffusion of agricultural techniques. 3 Cannabis species in the wild had a weedy attitude, growing in soils with high concentrations of nitrogen released by animal dejections and human activities. 2 The long coexistence between mankind and hemp led to an early domestication of the plant, which soon showed an amazing spectrum of possible utilizations. Hemp has been used as a source of textiles, as an edible plant, 4 and as a medicinal and psychoactive plant 5 (resins produced by secretory glandular trichomes). In recent times, hemp fibers have been used to produce bioplastic and antibacterial agents; moreover, the trichomes are considered as biofactories of phytochemicals with multiple biotechnological applications. 6 The extent of Cannabis domestication has been so persistent to cause the disappearing of the wild species: nowadays, the specie(s) belonging to the genus Cannabis are represented by myriads of cultivated varieties, which occasionally escape cultivation and grow also in the wild, giving life to forms that lose some features typical of cultivated ones. For this reason, the nomenclature of Cannabis has unstable foundations and has been the object of numerous taxonomic treatments. To fully understand the difficulties in applying a shared nomenclature to Cannabis, a digression is necessary to describe what is a species ( Table 1 ) and what means to give a name to a species.

Table 1.

What Is a Species: A Biological (and Nomenclatural) Dilemma

“There is no consensus on how to define a species, and likely never will be.” 19 Despite this discouraging preamble, we will try to present some basic information. The following definitions are among the most diffused in the species-definition debate over the last 50 years.
Biological species concept 30
“Species are groups of interbreeding natural populations that are reproductively isolated from other such groups.”
Diagnostic concept 31
A species can be defined as “the smallest aggregation of population (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals.” 31 According to this definition, a species is limited by a definite set of characters, which, traditionally, are morphological.
Genealogical species concept 32
A species is represented by populations that constitute a single group, without any exclusive subgroup. All the members of the group share a common ancestor (monophyly).
Ecological species concept 33
“A species is a lineage (or a closely related set of lineages), which occupies an adaptive zone minimally different from that of any other lineage in its range and which evolves separately from all lineages outside its range. A lineage is a clone or an ancestral-descendent sequence.”
There are unsolved difficulties in applying any of the definitions listed above, whatever the adopted: “every group differs in the biological criteria impacting species divergence, setting up a sliding scale from well defined to problematic species.” 34

An Outline of Nomenclatural Rules in Botany

Naturals sciences rely on shared nomenclatural rules. Although this statement sounds obvious now, it was not so for centuries, until at the beginning of the 18th Century became evident that there was a need to develop efficient nomenclatural tools for handling an increasing number of organisms. Naturalists during the 16th and 17th Centuries applied to species names that were actually short descriptions (polynomial system). The tendency toward a simplification of nomenclature was already evident in the Pinax Theatri Botanici, written in 1623 by Caspar Bauhin, 7 but only in the mid of 18th century Carl von Linnaeus provided a new framework to nomenclature, recommending in his Species Plantarum 8 that each species should be designated by a nomen trivialis, formed by the union of the generic name with a single word (epithet). By the second half of 18th century, this binomial nomenclature was adopted worldwide, and the need for a set of nomenclatural rules was already raised by JB Lamarck at the end of the same Century. 9 The first formalized laws for the nomenclature of plant species were prepared by Alphonse De Candolle in 1867, 10 but only in the 20th century both botanists and zoologists produced Codes of nomenclature, accepted by the international community of scholars. As far as botany is concerned, the International Code of Botanical Nomenclature has set up the rules for naming plants starting from the International Botany Congress held in Vienna in 1905. 11 However, the first Code accepted by the botanist community is the Cambridge International Code 12 and only after the Second World War a regular update of the Code has been carried out every 6 years. Since its last edition, 13 the Code has been renamed as the International Code of Nomenclature for Algae, Fungi, and Plants (ICN). The system proposed by the ICN is closed and hierarchically arranged ( Table 2 ).

Table 2.

A Simplified Summary of the Hierarchical Organization of the International Code of Nomenclature for Algae, Fungi, and Plants

Taxon: a taxonomic group of any rank
The taxa of one rank exclude each other
The name of a taxon is ruled by:
1. Publication validity;
2. Priority;
3. Typification;
The species is the core taxon of the system
The rank below the species is the varietas
Varietates showing pattern of affinity are grouped into subspecies

A taxonomic group of any rank (generically called taxon) can be considered as valid if: (1) it has been regularly published; (2) it has not been diversely and correctly named before (priority); and (3) it has been typified. A type is a material on which the description of a taxon is based. In the case of a plant species, it is generally a herbal specimen. The specimen on which the description is based is called the holotype ( Table 3 ).

Table 3.

Handling Nomenclature Principles

How to give a valid name to a species—some basic rules
1. Check if your putative new species has been already described and correctly erected. If not:
2. Write a protologue, which is a description of the morphological diagnostic features of the new species, and draw a sketch of the specimen (the iconotypus). Description and drawings should be carried out on an individual plant that represents the species: the holotypus.
3. The holotypus should be preserved in an official repository (i.e., an Herbarium).
When a name of a species need to be reexamined
1. If it is a nomen nudum (someone gave a name, but he didn’t write the protologue)
2. If the same species has already been correctly named (priority)
3. If it has not been typified

All nomenclatural rules included in the Code are based on the taxon system, and this architecture raises some important questions. The hierarchical system of taxa, although the Code is scientifically neutral and provides only a series of conventional rules, is deeply rooted into evolutionary theory. Most practitioners in nomenclature consider a taxon as a monophyletic entity 14 and arrange the nomenclature according to the current opinions on plant phylogeny. This tendency is particularly evident when new taxa are created or separated following molecular approaches, for example, DNA barcoding. 15 What is the position of cultivated plants like Cannabis in this framework? It is acknowledged that the botanical entities known as cultivated varieties are a product of human selection and cannot be assimilated to wild varietates. In contrast to these latter, cultivated varieties (cultivars) are a product of human activity and are not subjected to the selective pressure of the environment. 16 This argument has been largely debated, and the idea that cultivars should be considered as a separate matter is not new. Linnaeus was the first to place cultivated plants under a separated category, suggesting the adoption of different nomenclatural rules for them. 17 However, it was not until 1953 that the first edition of the International Code of Nomenclature for Cultivated Plants (ICNCP) was published. 18

The first and foremost principle of the ICNCP is that the names of cultivated plants cannot be handled using the system of taxon, which is replaced by the culton (a systematic group of cultivated plants). 19 The core entity of the nomenclatural system for cultivated plants is the cultivated variety or cultivar ( Table 4 ). Each cultivar is the product of human selection and is directed toward definite goals related to human activities. The cultivar can be reproduced and is not subjected to extinction. The nomenclatural system of cultivars is open: each name of a cultivar is not exclusive and the same cultivar could have different names, depending on the scope of the classification. 16 Cultivars are static units; they are defined by a set of characters and are linked to a standard, generally a specimen, or a document. 19

Table 4.

Some Basic Rules for the Nomenclature of Cultivated Plants

Culton: a systematic group of cultivated plants
Cultivar: a cultivated variety, uniform and stable in its characters
Group: an assemblage of similar cultivars on the basis of defined characters
The name of a cultivar or Group is the combination of the genus, or lower taxon to which it is assigned, with a cultivar or group epithet
The epithet can be a vernacular word of any language and should be not written in italics
The epithet is bounded by single quotation marks

The Classification of Cannabis

The existence of cultivated and wild entities of hemp dates back to Dioscorides and passing from the physicians and botanists of the Renaissance (the German botanist Leonardt Fuchs was the first to adopt the term sativa, for indicating the domesticated hemp 20 ) survived until the 18th Century, when Linnaeus in Species Plantarum 8 described a single species of hemp, Cannabis sativa. Later, Jean-Baptiste Lamarck 9 proposed two species of Cannabis: C. sativa, the species largely cultivated in the western continents, and Cannabis indica, a wild species growing in India. 21 The taxonomic treatment of Lamarck was rejected about 50 years later by J. Lindley, 22 who restricted Cannabis to C. sativa, following Linnaeus’ classification, and the concept of Cannabis as a monospecific genus was confirmed in the following century. Only in the second decade of 1900’s a new species, Cannabis ruderalis, 23 was erected, whereas the reinstatement of the species C. indica was more recently suggested by Schultes et al. 24 In more recent times, genomic DNA studies to classify C. sativa have been carried out using Cannabis varieties of different geographical origin. The results seem to suggest that a polytypic concept of Cannabis cannot be ruled out. 25 In addition, chemotaxonomical markers are a promising tool to identify different Cannabis accessions and to screen hybrids, taking into account that all Cannabis varieties intercross successfully and produce fertile hybrids. 26

A biphasic approach, combining morphological and chemical characters (fruit morphology and Δ 9 -tetrahydrocannabinol [THC] content) was adopted by Small and Cronquist, 1 who recognized the following four Cannabis taxa (all belonging to the single species C. sativa) that “coexist dynamically by means of natural and artificial selection”:

4. Cannabis sativa L. subsp. indica Small & Cronquist var. kafiristanica (Vavilov) Small & Cronquist.

According to the authors, both varietates belonging to the subspecies sativa are common in North America, Europe, and Asia and show a limited intoxicant potential. In contrast, the varietates of the subspecies indica have high intoxicant potential and grow mainly in the Asiatic Continent.

Recently, Small 2 has proposed two possible classification of Cannabis, one based on ICP, which confirms his previous taxonomical treatment, and a new classification system for domesticated Cannabis, which is based on ICNCP and recognizes six groups of cultivars as follows:

1. Group of the non-narcotic plants, domesticated for stem fiber and/or oil seed in Western Asia and Europe. Low THC and high cannabidiol (CBD);

2. Group of the non-narcotic plants domesticated in East Asia, mainly China. Low to moderate THC, high CBD;

4. Group of the narcotic plants domesticated in South Asia (Afghanistan and neighboring Countries), contains both THC and CBD.

In addition, there are also at least two stabilized hybrid groups with intermediate characters between the four groups ( Table 5 ).

Table 5.

Floral Characteristics of Cannabis

In 95% of Angiosperms (flowering plants), the flower contains both male and female reproductive structures, but in the remaining 5%, flowers bear either male or female reproductive structures. If the same individual bears both male and female flowers the plant is called monoecious, and if male and female flowers are produced by different individuals the plant is called dioecious.
Cannabis is a genus characterized by dioecy, with male individuals showing short life cycle, and higher and slimmer shoots compared to female ones, but cultivars that produce also hermaphrodite or monoecious flowers (bearing separate male and female flowers on the same individual) are well known. 35
Hybridization is the merging of differing gene pools to create offspring. Cannabis is wind pollinated; male plants produce vast amounts of pollen that can spread over large geographical areas, allowing the pollination of female flowers of plants growing very far from pollen-bearing flowers.
The extensive cultivation of Cannabis plants and the absence of barriers, which reduce or constrain interbreeding, lead to the production of numerous fertile hybrids that can maintain their characteristics over different generations. 1,24

This recent systematic treatment calls attention to the still existing practical difficulties of applying the International Code of Nomenclature to the genus Cannabis. Small 2 is careful in the application of the code, and this cautious attitude is the consequence of the perplexity about considering Cannabis exclusively as a cultivated plant. The studies of last two decades suggest that Cannabis, as other crops, exists in the so called crop–weed complexes, which are formed by cultivated forms and weedy forms escaped from cultivations and growing in the wild. These latter can establish new characters and are newly under the pressures of natural selection. Thus, it seems difficult to circumscribe Cannabis solely as a cultivated plant. In our opinion, an application of the taxon system to the genus Cannabis together with the sativa/indica distinction should be avoided, as recently suggested. 28 Due to the prevalent economic interest of the cultivated varieties of Cannabis, a simplified nomenclature system based on ICNCP should be applied. According to ICNCP, it is not mandatory to use the species epithets, sativa or indica, and a combination of the genus name and a cultivar epithet, in any language and bounded by single quotation marks (i.e., Cannabis ‘fibranova’, to cite a cultivar largely cultivated for fiber production), defines an exclusive name for each Cannabis cultivar.

However, due to its numerous medical and recreational usages, hundreds of Cannabis cultivated varieties have been developed and named with vernacular names by medical patients and recreational users. Few of these can be treated as real Cannabis cultivars, having been regularly named and registered according to the ICNCP, but many others, particularly marijuana strains, lack an adequate description and a standard. For this reason, their names cannot be accepted as cultivar epithets. Any strain that has not been formally described as a cultivar, for example, the so called Sour diesel, or Granddaddy Purple, should be named as follows: Cannabis strain Sour diesel, or strain Granddaddy Purple, with their popularized name without single quotation marks, having in mind that their names have no taxonomical validity.

Abbreviations Used

CBD cannabidiol
ICNCP International Code of Nomenclature for Cultivated Plants
ICN International Code of Nomenclature for Algae, Fungi, and Plants
THC tetrahydrocannabinol

Acknowledgment

The author gratefully acknowledges Prof. Daniele Piomelli, who critically read the article and made very helpful suggestions.

Author Disclosure Statement

No competing financial interests exist.

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Cite this article as: Pollio A (2016) The name of Cannabis: a short guide for nonbotanists, Cannabis and Cannabinoid Research 1:1, 234–238, DOI: 10.1089/can.2016.0027.