Annual herb 20 cm - 6 m tall Stem: upright. Leaves: mostly opposite (upper ones commonly alternate), palmately compound with three to nine leaflets (upper ones with fewer or no leaflets), stalked. Leaf stalks 2 - 7 cm long. Leaflets whitish green with yellowish brown resinous dots beneath, darker green above, 3 - 15 cm long, 2 mm - 1.7 cm wide, linear to narrowly lance-shaped, coarsely saw-toothed, appressed-hairy beneath, with large, stiff hairs above. Flowers: either male or female, borne on separate plants (dioecious), greenish, small, without petals. In some cases, as with many cultivars, the male and female flowers are on the same plant. Male flowers short-stalked, with 2.5 - 4 mm long, egg- to lance-shaped, minutely hairy sepals. Female flowers more or less stalkless, enclosed by a glandular bractlet, and subtended by a bract. Fruit: a lens-shaped achene, enclosed inside the enlarged perianth (the sepals and petals, collectively), white to greenish, mottled with purple, 2 - 5 mm long, egg-shaped, somewhat compressed, subtended by a bract. Male inflorescence: an upright, loose, compound cluster of flowers. Female inflorescence: a small, axillary cluster of flowers on a short, leafy branch.
Similar species: See the Notes section and also the links to the other Cannabis species.
Habitat and ecology: Introduced from Eurasia. Grows as a weed in waste ground, along fences, and in pastures. Many wild plants in the Chicago Region are from a strain originally cultivated for hemp fiber.
Occurence in the Chicago region: non-native
Notes: Many populations are the result of escapes from regular and clandestine cultivation. It has been cultivated for a long time, and its tough, durable fiber was used to make rope, paper, and a multitude of other useful products. This, in turn, caused it to spread around the world. For more information on the taxonomy of this plant see Cannabis sativa at the following link.
Etymology: Cannabis comes from the Greek word kannabis, meaning hemp. Sativa means cultivated.