THC in Hemp - Economic Botany

“Relatively little information is available on
the inheritance of THC, although it is clear that
it is polygenic. Based on over two dozen combinations
of different accessions, Small and
Beckstead (1979) found that the majority of first
generation hybrid crosses were intermediate in
THC content between their respective parents,
showing no dominance toward either parent”

THC in Hemp - Ernest Small.pdf (1.3 MB)


Trichome Development

“Abstract Most tetrahydrocannabinol (THC) of Cannabis sativa is located in the resin heads of capitatestalked glandular trichomes. We found that after
harvest the resin heads shrink in diameter in exponential decay fashion under ambient room conditions,
losing about 15 % in the first month, rising to 24 %
over the first year, 32 % by 50 years, and 34 % after a
century. An equation accounting for the asymptotic
curve descriptive of the progression of shrinkage
was determined [original gland head diameter
in microns = observed diameter divided by
(0.5255 ? 0.4745 multiplied by time in days to the
power -0.1185)], so that if the age of a specimen is
known, the original diameter of the gland heads in the
fresh state can be extrapolated. This equation was
employed to compare gland head size in samples of
different ages. A sample of high-THC medical
marijuana strains marketed under license possessed
resin head diameters averaging 129 lm, while a
sample of low-THC industrial hemp cultivars possessed gland head diameters averaging 80 lm. The
mean volume of the resin heads of the narcotic strains
was more than four times larger than that of the
industrial hemp strains. This is the first documented
report of a consistent morphological separator of elite
narcotic strains and non-narcotic plants. Most recognized strains of marijuana were bred clandestinely and
illicitly during the last half century. The occurrence of
large resin gland heads in a sample of officially
marketed pharmaceutical strains is an obvious correlate of selection for higher quantity of resin
Keywords Cannabinoids Cannabis sativa
Glandular trichomes Hemp Marijuana THC”

Size Matters - Ernest Small.pdf (1.1 MB)