Cannabis plant diversity
The cannabis plant has been growing on Earth since at least the last ice age, around 12,000 years ago. Due to travel, cultivation, selective breeding, trade and global seafaring, numerous varieties of the cannabis plant grow on all continents; cannabis finally arrived in South America in the 15th century (Merlin and Clarke 2013:128). It is one of the most widely disseminated cultivated plants in the world (Schultes et al. 1975:22).
Cannabis grown in colder, northern climes at low altitudes, where ultra-violet light intensity is low, generally produces high-quality fibre but little of the psychoactive resin, which is at highest concentrations in the upper leaves surrounding the buds of the mature female plant. Although the naturally produced resin content of different varieties of the plant varies considerably, one of the main factors governing resin production is ultraviolet light, which is produced by the plant primarily to protect the buds and repel predatory insects.
During the 1980s I spent most summers trekking in the Himalayas. I trekked through nearly all areas of the western Indian Himalayas (Kashmir, Himachal Pradesh, Uttaranchal) and several regions of Nepal, travelled through all of Eastern Tibet (east of Lhasa), and visited the mountainous region of southern Yunnan Province in China. I once calculated that I may have trekked around 2,000 kilometres in these mountainous regions. These journeys provided a magnificent opportunity to observe at close quarters native cannabis plants in a relatively wide geographical area.
If you travel through just one region of the world where cannabis grows wild and abundantly, such as in parts of the Indian and Nepalese Himalayas or Yunnan, you can see that there are numerous varieties of the plant in a small geographical region. Many kinds of cannabis plant grow wild; in and around villages you may also see cultivated fields (bagīcā) of single strains of the plant.
Mature plants of different strains, both broad-leaf and thin-leaf, may vary in height from between under a metre up to six or seven metres. The colour of the leaves ranges from yellowish to light or dark green, and even to deep purple, with no green leaves at all. Leaf formations may comprise two, three, five, seven, or nine members. The female buds may grow to a centimetre long or up to nearly half a metre in length. Seeds may be tiny and black or large and green, yellow or brown.
The psychoactive resin content of the upper leaves and buds of mature female plants also varies enormously. I have observed during the caras-rubbing season in the Himalayas in Octoberthat some small, spindly, purple/dark green plants, just one metre in height, may produce a surprising amount of high-quality resin, while a seven-metre high, pungent-smelling plant growing nearby with large buds growing at 2,500 metres produces virtually none.
The diversity of local plant varieties in the Himalayas has most probably resulted from historical selective breeding for either resin, oil (from the seeds) or fibre, some varieties being more productive of either resin or fibre. When I made these observations in the early 1980s, I was familiar with the tripartite classification of cannabis—as Cannabis sativa, Cannabis indica and Cannabis ruderalis—but only more recently has research clarified a greater diversity of cannabis species.
The botanical classification of cannabis plant species probably began in 1542 with the identification and image of Cannabis sativa in a work on plants (De historia stirpum commentarii insignes) by the German physician and botanist Leonhart Fuchs (Russo 2007:1616). More than 200 years later, Carolus Linnaeus, the Swedish “father” of modern botanical classification, also identified Cannabis sativa from specimens growing in Holland and Sweden (Stearn 1975:17) in his 1753 compendium Species Plantarum.
The classification of the cannabis into Cannabis indica (“Indian cannabis”)and Cannabis sativa (“cultivated cannabis”)began with the Frenchman Jean-Baptiste Lamarck in his Encyclpédie méthodique, publishedin 1785 (Schultes and Hofmann 1980:88). Lamarck was of the opinion that the indica variety was the kind native to India and Persia. Cannabis ruderalis (“roadside cannabis”), a small (two feet high), dark green, weedy variety found primarily in parts of Russia, was subsequently added to the classification in 1924 (Conrad 1993:60; Merlin and Clarke 2013:316), making a tripartite classification of the naturally growing cannabis plant. It was, however, only in the 1960s that botanists became fully persuaded that cannabis is not a monotypic plant but is, rather, polytypic (Schultes et al. 1975:24).
Although still adhered to by consumers, growers and suppliers, with the current awareness of the diversity of plant types, referred to above, this three-type classification of cannabis now seems inadequate (Merlin and Clarke 2013:317–331).
Ongoing research suggests that the cannabis plant may have originated in at least two regions, in Eastern Europe and Central Asia (or the western Himalayas), resulting in at least two main varieties, which may have possibly resulted from early human selection and cultivation. The current, general consensus is that Cannabis sativa strains have thinner leaves, are taller, more spindly—with less dense branch formations—and are generally reputed to have a proportionally higher component of THC, while Cannabis indica strains have broader leaves, are shorter, and are reputed to be higher in CBD, with less THC. Naturally-grown Cannabis ruderalis has a low THC and CBD content. (THC provides the stimulating “high” of cannabis, while CBD has a generally non-psychoactive, sedating effect.)
Based on extensive research, particularly by Karl Hillig at Indiana University, Merlin and Clarke (2013:xi) tentatively classify ten historical strains of cannabis originating in Europe and Asia.
Three kinds are putative “ancestor” varieties:
1. A putative hemp “ancestor” variety from the Balkan peninsula and Caucasus mountains, extant during the last ice age;
2. A putative drug “ancestor” from the Hengduan mountain region and Yungui plateau of South-west China, extant during the last ice age;
3. A broad-leaf hemp ancestor from East Asia.
Besides these putative “ancestor” varieties, also identified are four kinds of Cannabis indica (two broad-leaf and two narrow-leaf varieties):
4. A broad-leaf drug variety, Cannabis indica ssp. afghanica, from northern Afghanistan and Pakistan;
5. A broad-leaf hemp variety, Cannabis indica ssp. chinesis, from China, Korea, Japan, and South-east Asia;
6. A narrow-leaf drug variety, Cannabis indica ssp. indica, from South and South-East Asia, and the Middle East;
7. A narrow-leaf drug “ancestor” variety, Cannabis indica ssp. kafiristanica, from the Himalayan foothills, from Kashmir to Myanmar.
Two varieties of narrow-leaf Cannabis sativa are specified:
8. A narrow-leaf hemp variety, Cannabis sativa ssp. sativa, from Europe;
9. A narrow-leaf hemp “ancestor” variety, Cannabis sativa ssp. spontanea, from Eastern Europe and Central Asia.
Also classified is:
10. Cannabis ruderalis, from northern Central Asia, which is possibly an “ancestor” of both Cannabis sativa and Cannabis indica varieties.
There are also nowadays numerous hybrid strains of the three main types of cannabis plant. The diversity of native species of cannabis has been further complicated since Californian entrepreneurs began—again—selective breeding of high-yield resin plants on the island of Maui in the early1970s, the famous Maui Wowie (see ‘Ohana 2016) being one of the first produced in recent times in commercial quantities. The global cross-breeding of various species of the plant and the trans-continental transportation of seeds—for example, of Mexican seeds to Morocco in recent years—has led to an even greater diversity of cannabis plant types.
Although the two main strains of cannabis, Cannabis indica and Cannabis sativa, are still reputed to have, respectively, either higher CBD or THC content, this does not hold true for many varieties of the plant. The widely varying content of either CBD or THC in various plant types, which may have resulted historically from selective breeding by humans (Merlin and Clarke 2013:319ff.), has led some commentators to doubt if the general distinction between higher CBD Cannabis indicas and higher THC Cannabis sativas is still valid. De Meijer (2016:90) remarks that there are no strict natural relationships between fibre characteristics and cannabinoid content. The sativa/indica distinction is perhaps still useful as a general guide to probable CBD or THC content, but many old and new strains confound such a simple distinction. That said, these days far more information is usually provide by seed companies about the chemical content of different cannabis strains.
Global research into the cannabis plant is continuing to reveal its complex chemistry, and how selective breeding of different strains can be refined not only for specific medical conditions, material industry or food, but for subtle variants of inebriation, to provide the appropriate concentration, inspiration and effect in as many circumstances as practical.
Clarke, Robert C., and Mark D. Merlin (2013). Cannabis: Evolution and
Ethnobotany. Berkeley/Los Angeles/London: University of California Press.
Conrad, Chris (1993). Hemp: Lifeline to the Future (The Unexpected Answer for Our
Environmental and Economic Recovery). Los Angeles: Creative Xpressions
Meijer, Etienne de (2016) . ‘The Chemical Phenotypes (Chemotypes) of
Cannabis’. In Roger G. Pertwee (ed.), Handbook of Cannabis, pp. 89–110.
Oxford: Oxford University Press.
‘Ohana, Pua Mana (2016). ‘The History of the Maui Wowie Strain’. Seedsman.com.
Russo, Ethan B. (2007). ‘History of Cannabis and Its Preparation in Saga, Science,
and Sobriquet’. Chemistry and Biodiversity, vol. 4, pp. 1614–1648.
Schultes, Richard Evans, and Albert Hofmann (1980). The Botany and Chemistry of
Hallucinogens. Springfield, Illinois: Charles C. Thomas.
Schultes, Richard Evans, William M. Klein, Timothy Plowman, and Tim E.
Lockwood (1975). ‘Cannabis: An Example of Taxonomic Neglect’. In Vera
Ruben (ed.), Cannabis and Culture, pp. 21–38. The Hague/Paris: Mouton
Stearn, William T. (1975). ‘Typification of Cannabis sativa L.’. In Vera Rubin (ed.),
Cannabis and Culture, pp. 13–20. The Hague/Paris: Mouton Publishers.