cannabis
- Kingdom: Plantae
- Division: Angiosperm
- Order: Rosales
- Family: Cannabaceae
How many species of Cannabis are there?
What distinguishes marijuana from hemp?
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cannabis, (genus Cannabis), genus of 1–3 species of aromatic flowering plants cultivated for fiber, oilseed, medicinal preparations, and psychoactive products. Native to Central Asia, cannabis is now grown worldwide in a range of forms adapted for different uses. The taxonomy of the group is contentious, with many botanists holding that the genus comprises a single species, Cannabis sativa. Cannabis plants are typically grown as hemp, which is a source of fiber and other industrial products, or as marijuana, which is cultivated for its psychoactive and medicinal properties. In the United States and Canada, hemp is legally defined as cannabis containing no more than 0.3 percent tetrahydrocannabinol (THC)—the psychoactive component of marijuana—by dry weight. In comparison, marijuana varieties are bred for their THC content and may contain 25 percent THC or more. See also medical cannabis.
Physical description
Cannabis plants are erect, aromatic, and herbaceous. The distinctive, palmately lobed leaves are borne oppositely along the stems. Hemp plants cultivated for fiber average 2–3 meters (6–10 feet) tall with almost no branching, whereas hemp plants grown for oilseed are shorter and many-branched. Marijuana plants are typically female and are shorter and many-branched.
The plants are dioecious, meaning that individuals are either male or female. The flowers of both sexes are small, greenish-yellow, and lack petals. Seed-producing, or pistillate, flowers form elongate spikelike clusters on female plants. Pollen-producing, or staminate, flowers form many-branched clusters on male plants. The dry fruits are achenes and each contains a single edible seed.
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Species
The number of species in the genus Cannabis has long been a subject of taxonomic debate. Morphological differences in wild and cultivated forms of cannabis have introduced taxonomic uncertainties, and all forms are able to interbreed (a trait not uncommon for related plant species). Many botanists treat the genus as monotypic, consisting of a single species, C. sativa. The plant is thus considered polymorphic, meaning it has a wide range of possible morphology and chemical composition. Under this classification, forms commonly referred to as C. indica and C. ruderalis are considered subspecies or varieties of C. sativa.
Other researchers, however, recognize two or three distinct species—C. sativa and C. indica, and sometimes C. ruderalis—based on differences in plant stature, branching patterns, geographic origin, and cannabinoid profiles. For example, C. indica is often described as shorter and more highly branched than C. sativa, while C. ruderalis is typically smaller and associated with weedy or wild populations. To add to the confusion, growers and sellers frequently label marijuana and cannabis products as “sativa” or “indica,” often to indicate differences in the ratios of THC to cannabidiol (CBD, another cannabinoid), but these terms do not always correspond to the species of origin.
