While oilseed hemp has much more economic potential thanfiber hemp, humans
have not yet alteredC. sativafor this purpose to the same astonishing extent that
fiber hemp has been selected forfiber production and marijuana strains have been
selected for THC production. The fundamental distinction between biotypes spe-
cialized forfiber and THC is universally recognized by the labels“hemp”and
“marijuana,”and this simple folk classification is deserving of parallel scientific
classification. It is recommended that hemp plants be recognized asC. sativa
subspeciessativa, and marijuana plants asC. sativasubspeciesindica.
There is evidence of two somewhat distinctive classes of marijuana plants,
commonly referred to as‘indica”and“sativa”(which is very misleading because
both are high in THC, where“sativa”as a term has traditionally been applied to
low-THC plants). “Indica-type” plants are reputed to have lower THC (and
appreciable CBD) compared to“sativa-type,”but today so much hybridization has
occurred that the distinction is of doubtful value, and it may be preferable to simply
characterize marijuana strains by their chemical composition.
In parallel to the contention that there are two kinds of marijuana plants, there is
evidence that Chinese hemp is somewhat distinctive from European hemp. Once
again, so much hybridization has occurred that the distinction is of doubtful tax-
onomic value, although for breeding purposes knowledge of such differentiation is
invaluable for producing new vigorous cultivars.
There is limited evidence of an ancient east-west Eurasian differentiation of
domesticatedCannabis, perhaps the result of a genetic bottleneck of European
stock selected from Asia. Some botanists have labelled the European stock as“C.
sativa”and the Asian stock as“C. indica.”However, the genetic differentiation is
too weak to merit any taxonomic recognition, and extensive world-wide trans-
portation of different forms ofC. sativathroughout the world, and accompanying
hybridization, has obscured possible differences.
MostCannabisplants growing outside of cultivation possess adaptive features
suiting them to the stresses of wild existence, while plants that have been domes-
ticated (for stemfiber, oilseed or THC production) are collectively distinguishable
by notably reduced development of the same features. Nevertheless, considerable
genetic interchange occurs readily between wild-growing and cultivated plants, so
that there is continuous variation between them on a global basis. The wild-growing
plants in north temperate regions (especially in northern Eurasia and North
America) are typically low-THC relatives of hemp (and so may be assigned with
hemp toC. sativasubsp.sativa). In parallel, the wild-growing plants in more
southerly regions (especially in southern Asia) are often relatives of marijuana
plants, frequently developing elevated levels of THC (and so may be assigned with
marijuana plants toC. sativasubsp.indica). As presented in the text, the very
distinctive seed features of wild plants may be employed to distinguish them (as
taxonomic varieties) from their domesticated counterparts, although for most
practical purposes the distinction of“hemp” and“marijuana” classes of plant
suffices.
Acknowledgements Thefigures were prepared by B. Brookes.
1 Classification ofCannabis sativaL. in Relation... 55