Cannabis ( Cannabis sativa L.), including Cannabis indica, wild cannabis and industrial hemp, is a plant grown for its textile bast fibre or long fibre. Its different parts contain THC (tetrahydrocannabinol) in different concentrations. Cannabis belongs to the Cannabaceae family, Cannabis L. genus and is a typological species. Cannabis indica Lam. is native to Pakistan and Kafiristan. Wild cannabis (Cannabis ruderalis) grows in Mongolia, Manchuria, also Estonia but data on general distribution are not comprehensive.
Cannabis has upright stems and leaves that resemble fingers (Krall, H. et al. 1999). It has 5 to 9 (11) leaves with serrated edges. The plant is dioecious, less often monoecious. Male flowers form hanging panicles whereas the female flowers form spiky inflorescences. Female flowers are larger and have more leaves than the male flowers. It is a cultivated plant, its wild variety (Cannabis ruderalis) grows as weeds or alien species by the side of roads. The genus has been considered monotypic, although many authors consider some Cannabis sativa L. subtaxons as separate species (Kask, M. 1971).
Female (1) and male (2) plants
During the growth period, female and male plants are not distinguishable from each other. The plants acquire characteristic features during the growth period and dimorphism becomes visible. Male plants develop considerably faster and during flowering are yellower in colour, shorter and have less foliage than the female plants (Reimets, E., 1976). The male plant loses its scarce foliage after flowering and grows "small grapes" that contain approximately 5 stamens surrounded by a lot of yellow pollen. The male plant produces bigger stems and grows faster but the female plants produce better fibre.
The tight crowded clusters of the female flowers are situated around the top parts of the plant and enveloped by leaves. The female plants' flower heads have considerably more leaves than the male plants (Reimets, E., 1976). The ovary is almost completely covered, only two stigmas open to let the pollen in. The ovary is only one gray or brown seed with a diameter of about 5 mm. The seeds contain 17 to 38% of fatty oil (Kask, M. 1971).
Cannabis is an annual short-day plant. It gives a signal to start producing flowers at a certain point in time; this is related to the length of the day. The plant grows continuously, producing a leaf for every 79 to 85 degrees of accumulated temperature. This relationship between temperature and leaf node formation is very important and allows you to predict the quality of the fibre.
The lower and top parts of the stem are more or less round, the middle part is polygonal and has grooves. The entire stem is usually hollow inside, its surface is rough and covered with hairs. The stem is 1 to 4 m long with a diameter of 3 to 30 mm. The stem consists of 3 to 10 internodes, the length of an internode is around 5 to 40 cm. The fibres are somewhat weaker in the nodes than in the internodes (Reimets, E., 1976).