Cannabaceae is a small family of flowering plants, known as the hemp family. As now circumscribed, the family includes about 170 species grouped in about 11 genera, including Cannabis (hemp), Humulus (hops) and Celtis (hackberries). Celtis is by far the largest genus, containing about 100 species.[2]
Cannabaceae is a member of the Rosales. Members of the family are erect or climbing plants with petalless flowers and dry, one-seeded fruits. Hemp (Cannabis) and hop (Humulus) are the most economically important species.[4]
Other than a shared evolutionary origin, members of the family have few common characteristics; some are trees (e.g. Celtis), others are herbaceous plants (e.g. Cannabis).
Members of this family can be trees (e.g. Celtis), erect herbs (e.g. Cannabis), or twining herbs (e.g. Humulus).[2]
Leaves are often more or less palmately lobed or palmately compound and always bear stipules. Cystoliths are always present and some members of this family possess laticifers.
Cannabaceae are often dioecious (distinct male and female plants). The flowers are actinomorphic (radially symmetrical) and not showy, as these plants are pollinated by the wind. As an adaptation to this kind of pollination, the calyx and corolla are radically reduced to only vestigial remnants found as an adherent perianth coating the seed. A reduced and monophyllous cuplike perigonal bract, properly known as the bracteole, immediately surrounds and protects the seed and is often misnamed as a "calyx". Flowers are grouped to form cymes. In the dioecious plants the male inflorescences are long and look like panicles, while the female ones are shorter and bear fewer flowers. The pistil is made of two connate carpels, the usually superior ovary is unilocular; there is no fixed number of stamens.