Most people are aware that cannabis and hemp are closely related. In fact, many mistakenly believe that the two are one and the same thing. The latter cannot be farther away from the truth. But when it comes to a structural comparison, it takes a keen and informed eye to tell one apart from the other.
For starters, hemp and cannabis are somewhat joined at the hip as they originate from the same plant species which is Cannabis Sativa L.  However, they are from different subspecies. The major chemical difference between the two subspecies is found in the amounts of tetrahydrocannabinol (THC) in each. Hemp strains contain negligible amounts of THC, typically less than 0.3%. This amount of THC is negligible and consequently hemp strains cannot cause mental intoxication. This property of THC has legal ramifications; cannabis (high THC) is illegal under federal law while hemp (low THC) is not.
So how does this fit in with the physical structures of the two subspecies of cannabis sativa L.?
When it comes to physical structure the differences are minute, it takes a schooled eye to pick them out.
Structural Similarities Between Hemp and Cannabis
Hemp and cannabis plants have a similar physical appearance and hues. The leaves and flowers take different shades of green and some strains will spot purples, reds, or pinks. Orange colored pistils thread their way around the greens while a whitish layer of trichomes is seen on the surface of the buds during harvest. However, cannabis plants are likely to have a heavier coating of sticky trichomes since they produce more phytocannabinoids and terpenes.
Structural Differences Between Hemp and Cannabis
Because hemp is grown for industrial use the plants are grown close together to increase the fiber content. The plants will be tall and skinny and the leaves which grow at the top will be narrow. Cannabis plants on the other hand are cultivated to produce cannabinoids. Therefore, the plants are likely to be short and bushy with broad leaves. Cannabis buds are also likely to be dense and low-lying when fully mature.
As mentioned earlier, cannabis buds are likely to spot a heavy layer of trichomes which is visible when the plants are mature and ready for harvest. As for hemp, this silvery layer may not be visible due to the reduced cannabinoid content.
As much as hemp and cannabis are very similar structurally there are few things that can help you tell them apart.
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- Small E. Classification of Cannabis sativa in Relation to Agricultural, Biotechnological, Medical and Recreational Utilization. In: Chandra S., Lata H., ElSohly M. (eds) Cannabis sativa L. – Botany and Biotechnology. Springer, Cham, 2017, pp 1-62.