permitted the cultivation of cultivars with higher levels. It is well known in the illicit
trade how to screen off the more potent fractions of the plant in order to increase
THC levels in resultant drug products. Nevertheless, a level of 0.3% THC in the
flowering parts of the plant is reflective of material that is too low in intoxicant
potential to actually be used practically for illicit production of marijuana or other
types of cannabis drugs. While this criterion is in common use to separate adult
plants, the ratio of CBD and THC often suffices to distinguish high-THC and
low-THC plants as young as seedlings (Rowan and Fairbairn 1977 ; Broséus et al.
2010 ; De Backer et al. 2012 ). However, Vogelmann et al. ( 1988 ) found that the
cannabinoids of extremely young seedlings were dominated by cannabichromene,
and de Meijer et al. ( 2009 ) also observed that cannabichromene is often dominant in
juvenile plants and young cuttings.
Sativa-type marijuana strains characteristically have very high THC level in the
cannabinoids, and no or small amounts of CBD. They are higher in THC than most
indica-type marijuana strains, hence more popular, although harder to grow indoors
where room height is limited, because of their tallness. Hybrids between the two
groups have proven to be well adapted to indoor cultivation and are progressively
being marketed (Clarke and Watson 2006 ). Increasingly, strains with alleged per-
centages of each type are being sold.
Strains of the indica-type group characteristically have moderate levels of both
THC and CBD in their cannabinoid profile. Like the sativa-type, the indica-type has
historically been employed to produce hashish in southern Asia, particularly in
Afghanistan and neighboring countries. Hashish is prepared by pooling collections
from many plants, so individual plants may vary in proportions of cannabinoids
(i.e., not all plants necessarily have moderate levels of both THC and CBD). In
Asia, strains of both kinds were often used to prepare hashish, but in most Western
nations they are predominantly employed to prepare marijuana. Traditional Asian
hashish is typically rich in both the intoxicant THC and the non-euphoriant CBD,
and indica-type land races have been particularly selected for making hashish. By
contrast, most high-THC sativa cultivars have been selected just for THC, and
indeed most have limited or no CBD. An explanation for the presence of CBD in
traditional hashish land races was offered by Clarke and Watson ( 2006 ):“Hashish
cultivars are usually selected for resin quantity rather than potency, so the farmer
chooses plants and saves seed by observing which one produces the most resin,
unaware of whether it contains predominantly THC or CBD.”
Geographical biotypes have been found with one or more rare cannabinoids in
unusually high presence, which is probably the result of genetic drift (change in
allele frequencies occurring in small populations simply by haphazard survival).
CBC is a frequent minor constituent of highly-intoxicating strains ofC. sativa,
especially from Africa, and strains high in CBC have been selected for medicinal
experimentation. De Meijer et al. ( 2009 ) provided evidence that CBC is present in
substantial amounts in juvenile plants and declines with maturation. These authors
found plant variants in which CBC persisted into maturity, and noticed that this is
associated with a reduced presence of perigonal bracts and secretory glands. Potter
( 2009 ) recorded a greater presence of CBC in the small (non-stalked) secretory
32 E. Small