The Linnean Society of London preserves in Linnaeus' herbarium two specimens of Cannabis sativa. One specimen, No. 1177.1, is labeled "sativa" in Linnaeus' handwriting and represents a staminate plant, with much more abbreviated leaves than is usual in the genus. No. 1177.2, without a specific epithet written on the sheet, represents a pistillate plant with the lanceolate leaves that are normal for the species. There are, of course, no locality data on these two specimens, although in Species Plantarum, Linnaeus offers the information that the species has a "habitat in India." In his annotated copy of Species Plantarum, which is preserved at the Linnean Society, Linnaeus had written, in his own hand, as a note for a further edition, the word "Persia" as an additional habitat.

 

From this time on, many subsequent species of Cannabis were noted, and in 1862 Bentham and Hooker included the genus Cannabis as part of the family Urticaceae, which was assigned to the artificial series Unisexuales, along with the families Euphorbiaceae, Balanophoraceae, etc. Family Cannabaceae was recognized as separate and distinct from the Urticaceae by Rendle (1925) and Hutchinson (1926), while the remaining authors merged it with the family Moraceae.

 

The Moraceae are mostly arborescent (tree-like) and contain a milky latex. The lobes of the calyx are usually in fours, but are often reduced or absent. Stamens are usually equal in number and mounted opposite to the sepals; filaments are in-flexed or straight during the bud stage.

 

Cannabis, on the other hand, is hardly arborescent and contains clear resin. It also possesses short, straight stamens. The five-lobed calyx is fused in the female, but the lobes are free in the male flower. Thus, the classification of Cannabis in the family Cannabaceae (Cannabinaceae, Cannabiaceae, Cannabidaceae) along with the genus Humulus (hops) seems most correct.

 

The following table lists the "species" names of the various types of Cannabis. New members of the genus Cannabis were added to the list until 1960, when the validity of treating Cannabis as a polytypic genus was questioned. Vavilov, in consideration of the natural habitat of Cannabis, recognized that the freely growing type, which has "run wild" has enough distinct characteristics to single it out as a variety—Cannabis sativa var. spontaneadistinct from the cultivated variety. Zhukovskii (1964) considers the "weed-like" hemp of Russia to be a distinct species, Cannabis ruderalis. Cultivated hemp he names Cannabis sativa, noting that he has recognized taxonomically two races of C. sativa that have escaped cultivation, one large-fruited, the other small-fruited, with monoecious individuals in each race. He reserves a third binomial, Cannabis indica, for the narcotic-producing plant occurring wild in Pakistan and Kafiristan. Although Vavilov and Zhukovskii do not accept genetically stable varieties, they do argue here that C. ruderalis and C. indica could not be the ancestral types of C. sativa (cultivated hemp), and must therefore be considered separate species.

 

Mansfield establishes different categories, including C. indica, of Indian origin; along with two subspecies of C. sativa, both of which are cultivated and escaped; Cannabis spontanea (or Cannabis ruderalis), ranging from Afghanistan to middle Europe; and Cannabis culta of Asia, Europe, North Africa, North and South America, and Australia.

 

Several botanists today regard Cannabis as a monotypic genus much as Linnaeus did in 1753. However, his "varietas" cannot be treated as genetically distinct and botanically accepted varieties.

 

Different races have been positively identified on the basis of chemical composition of the psychoactive resin. These races may be termed chemovars and are divided into two basic categories. The drug phenotype is identified by a ratio of tetrahydrocannabinol to cannabidiol greater than one, while the fiber phenotype shows ratios lower than one. These chemovars breed true and maintain the ratios of tetrahydrocannabinol-to-cannabidiol of the parent material regardless of growing conditions, although the range of values will be narrower under growth conditions that do not favor growth of Cannabis in general.

 

Jens Schou and Erik Nielsen (1970) in a report by the United Nations Commission on Narcotic Drugs, concluded:

 

Experiments seem to indicate that the content of tetrahydrocannabinol in some plants is dependent on the variety of the plant rather than on the locality where it is grown.

 

Doorenbos, et al. (1971a), while studying variants of Cannabis, stated that they distinguished drug and fiber types chemically and went on to state: "The two phenotypes are well defined in nature, but hybrids of the two have been produced by controlled pollination."

 

Many cultivars (cultivated varieties) of Cannabis also exist that have been bred for such characters as low internode frequency, long stalks, even maturation of plants, fiber quality and fiber quantity, and cannabinoid level. Some cultivars, such as "Carmagnola" (Italy) and "Kentucky" (U.S.) are fiber types selected for maximum fiber yield.

 

Schultes, et al. (1974), believe that the genus Cannabis can be divided into three distinct species: C. sativa, C. indica and C. ruderalis. These distinctions, based on wood anatomy, growth habit, leaf variation, seed type, and chemical constituents, can be summarized as follows:

 

Key to "species" of Cannabis

 

1 - Plants usually tall, up to 2 to 6 meters (6 to 18 feet), laxly branched. Achenes (seeds) are smooth, usually lacking marbled pattern on outer coat (perianth), firmly attached to stalk and without definite articulation.

If the above is true the species is C. satiuti.

 

1a - Plants usually small, 1.2 meters (4 feet) or less, not laxly branched. Achenes usually strongly marbled on outer coat, with a definite abscission layer, dropping off at maturity.

Go to choice 2 or 2a.

 

2 - Plants very densely branched, more or less conical, usually 1.2 meters (4 feet) tall or less. Abscission layer a simple articulation at base of achene.

If the above is true the species is C. indica.

 

2a - Plants not branched or very sparsely so, usually 0.3 to 0.6 meters (1 to 2 feet) tall at maturity. Abscission layer forms a fleshy carbuncle-like growth at base of achene.

If the above is true the species is C. ruderalis.

 

Research by Small and Cronquist (1976) has shown an adaptive difference in fruit characteristics between wild (weedy, naturalized or indigenous) phase and domesticated (cultivated or spontaneous) phase. In the wild phase, natural selection favors small, mottled seeds with a thick pericarp (outer shell) that are readily disarticulated from the pedicel (point of attachment). These small seeds resist herbivores because of their protective coloration and pericarp, and are rapidly dispersed onto the ground, where their protective coloration is an advantage and germination may take place.

 

Domesticated types, on the other hand, do not come under these natural pressures, but are subject to the selective pressures of human cultivation.

Readily disarticulated seeds will not be present in harvested Cannabis since they will already have been dispersed. The next generation will be made up largely of individuals grown from persistent seed. Also, under the protective eye of man, resistance of seeds to biotic controls such as seed-eating herbivores is not of such importance.

 

By combining the parameters of the seed type with psychoactivity (A1-THC content), Small was able to define two subspecies and four varieties of the species Cannabis sativa L. as follows. Subspecies criteria are fulfilled before variety determination is made.

 

Key to Subspecies and Varieties of Cannabis sativa L.

 

1 - Plants of limited intoxicant ability, Ai-THC comprising less than 0.3% (dry weight) of upper, youhger leaves, and usually comprising less than half the cannabinoids in the resin. Plants are cultivated for fiber or oil, or growing wild in regions where such cultivation has occurred. If the above is true the subspecies is sativa.

 

la - Mature fruits are relatively large, seldom less than 3.8 millimeters (1/8 inch) long, tend to be persistent, lack a basal constricted zone, and are not mottled or marbled, the perianth is largely sloughed off.

 

If the above is true the variety is sativa.

 

1b - Mature fruits are relatively small, commonly less than 3.8 millimeters (1/8 inch) long, readily disarticulate from the pedicel, have more or less definite, short, constricted zone toward the base, tend to be mottled or marbled in appearance because of irregular pigmented areas of the largely persistent and adnate (attached) perianth.

 

If the above is true the variety is spontanea.

 

2 - Plants with considerable intoxicant ability, n'-THC comprising more than half the cannabinoids in the resin. Plants are cultivated for intoxicant properties, or grow wild in regions where such cultivation has occurred.

 

If the above is true the subspecies is indica.

 

2a - Mature fruits are relatively large, seldom less than 3.8 millimeters (1/8 inch) long, tend to be persistent, lack a basal constricted zone, are not mottled or marbled; the perianth is largely sloughed off.

 

If the above is true the variety is indica.

 

2b - Mature fruits are relatively small, usually less than 3.8 millimeters (1/8 inch) long, readily disarticulate from the pedicel, have a more or less definite, short, constricted zone toward the base, tend to be mottled or marbled in appearance because of irregular pigmented areas of the largely persistent and adnate perianth.

 

If the above is true the variety is kafiristanica.

 

In later research, although he does not differentiate between CBD and CBC, Small (1978) further divides the cannabinoid phenotypes (chemotypes) into the following four categories:

 

Phenotype I - resin composed mostly of THC"drug" type, with THC > 0.3%; CBD < 0.5%.

 

Phenotype II - resin composed of intermediate amounts of THC and CBD—potentially "drug" type, however, most individuals are low-THC "fiber" type, with 1.3% > THC > 0.3%; CBD > 0.5%.

 

Phenotype III - resin composed mostly of CBD"fiber" type with THC < 0.3%; CBD > 0.3%.

 

Phenotype IV - resin also contains CBGM (cannabinoid monomethyl ether), approximately 0.05%.

 

Phenotype I is restricted primarily to latitudes south of 30° north latitude; phenotype III is usually located north of 30° north latitude, while phenotype II is intermediate in location and may result from hybridization between types I and III. Type IV appears in northeastern Asia.

 

Small's research derives solely from seeded or (immature) pistillate plants on short growing seasons (45° north latitude). This is where the production of drug Cannabis begins and Small's research ends.

 

His conclusion that there is a strong correlation existing between high-THC cannabinoid phenotypes and cultural selection for potent strains does not take into consideration that his data also reflect that individuals of phenotype I, considered drug Cannabis, are usually grown south of 35° north latitude.

 

Possibly environmental parameters are of more importance than cultural selection in establishing cannabinoid phenotypes. Recent studies by Valle et al. indicate that Cannabis grown under 12 hours of light per day produces at least twice the THC of individuals grown under 10 hours of light per day; there are also variations in other cannabinoid levels. It seems logical that constant expo sure of equatorial Cannabis populations to at least 12 hours of light per day during the end of the growing season could result in natural selection for a high-THC (type I) phenotype regardless of other abiotic and biotic factors, Small goes on to mention that nearly 50% of phenotype I strains fail to mature enough to bear viable seeds in Ottawa (45° north latitude) and produce little or no CBN; so there is not a complete expression of chemotype. Also, there has been one "disquieting" observation that strains grown in Ottawa produce only 50% of the THC that the same strains do in Mississippi (35° north latitude), this difference is attributed to variations in humidity and temperature as well as in length of season. This observation illustrates additional direct environmental influences on THC production that might also influence the selection of phenotype.

 

Small hints at continued research to correlate morphological characteristics with chemotype, but indeed his research interests have currently switched to Humulus. I think more parameters should be investigated before taxonomic judgments are made. The divergent morphological characteristics of Cannabis strains are certainly a sound starting point, and are primary for taxonomic differentiation. By looking deeply enough, one might find chemotypes for micro-nutrient uptake, starch synthesis, or pigment content that have no correlation at all with cannabinoid production or morphology. Indeed, one might fall back upon the basic pretense that Cannabis sativa is fiber Cannabis and Cannabis indica is drug Cannabis. Turner et al. (1979) report that staminate and pistillate plants of the same strain may exhibit several chemotypes during various stages of maturity, if the chemotypic criteria of Waller or Small are applied.

 

Any classification is more semantic than scientific and data can be interpreted differently by various taxonomists. We must remember, however, that morphological characteristics are our most important key to distinguishing individual varieties, strains, or species and that adaptation to abiotic conditions determines the phenotypes. A Himalayan Cannabis indica plant and a Kentucky fiber Cannabis sativa plant grown under the same conditions year after year show morphological differences suggesting that at least two separate species should be defined. The compact stature, wide dark leaves, short internodes, high resin production, and acrid aroma of Himalayan Cannabis indica does not change markedly over years of cultivation in North America. These characteristics are so strong they often predominate in the offspring of hybrid crosses with Cannabis sativa.

 

Human pressures are also very important in creating the variation of Cannabis. As mentioned previously, some authors make a distinction between wild and cultivated varieties. Man has had his greatest effect on cultivated Cannabis by exerting genetic pressure (making selections year after year) for the type of plant that best serves his purpose. The two basic uses of Cannabis are the production of drug containing resin and of high-quality fiber, resulting in the two types of cultivated Cannabis most often noted. Selection for seed content might also be a factor, but is certainly minor compared to the other uses of the plant.

 

Botanists have made distinctions between drug and fiber varieties of Cannabis based on morphology, physiology, and chemical composition. Drug strains are often shorter than fiber strains, with closely spaced limbs and small dark seeds, as exemplified by varieties from Afghanistan, India, and Colombia. Fiber strains are usually tall with long internodes and very few limbs.

 

Physiologically, drug strains have evolved a definite dioecious condition, especially where staminate plants are removed to promote resin production in pistillate plants. On the other hand, fiber strains have evolved a monoecious tendency favoring even maturation and consistent sexual morphology throughout the crop. Bazzaz and Dusek (1971 and 1975) have shown differences in chlorophyll content, photosynthetic rate, transpiration rate, and drug content of strains from various climates and latitudes under differing growing conditions. They conclude that the various strains are ecotypes, each adapted to its own respective habitat and latitude.

 

Grlic (1968) reports that various stages in the "ripening" of Cannabis resin can be observed. In this sequence cannabidiolic acid (CBDA) is successively converted to cannabidiol (CBD), tetrahydrocannabinols (THC) and finally to cannabinol (CBN). Five ripening stages have been defined based on the progress of this phytochemical process: "unripe" (predominately CBDA), "intermediate" (CBD), "ripe" (THC), and "overripe" (CBN) along with a final stage for damaged or very old specimens termed "altered." He also notes that ripening seems more advanced in Cannabis from tropical areas (ripe and overripe stages) than in Cannabis from temperate climates (unripe and intermediate stages).

 

Variations in the aromatic principles of pistillate Cannabis flowers are also characteristic of race and origin. Although they are as difficult to describe as the bouquet of fine wine, the characteristic aromas and tastes of the various Cannabis strains from around the world are very consistent. Some of these traits are preserved in domestic populations, but many are lost; therefore they must be controlled by environment as well as genetics.

 

At this point the terminology of bract and calyx should be clarified. A review of the literature shows that much confusion exists around the nomenclature of the bracts on a Cannabis plant. The term bract most commonly refers to the membranous sheath surrounding the ovule which is herein referred to as the pistillate calyx or calyx. Bract is sometimes used to describe the stipule (leaf spur) which appears on both sides of the axis of the petiole (leaf stalk) with the stem. The term has also been used to describe the small reduced leaf that subtends each pair of calyxes. It is my contention that the word calyx should be used to describe the five-part carpel structure of the staminate flower or the five-part fused tubular sheath that surrounds the ovule and pistils. The word bract is perfectly acceptable for the small reduced leaf subtending a pair of pistillate calyxes, and stipule is the correct term for leaf spur, Calyx implies that the flower part is reproductive in nature, and bract has a distinctly vegetative connotation. It is unfortunate that bract has been so misused as it is really an excellent descriptive word for a small reduced leaf. To quote in part from Roget's Thesaurus, "Bract, bractlet — foliage, foliation, leafage, . . . stalk, leafstalk, petiole, . . . stipule, . . . leaf, . . . leaflet, . . . blade, lamina, . . . seedleaf, . . calyx leaf . . .. Calyx —sac, . . . pocket, vesicle, . . pericarp, . . . capsule, .. . pod . . .."

 

It seems obvious that bract describes leaf structure and calyx describes floral structure.