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Cannabaceae is a small family of , 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.Stevens, P.F. (2001 onwards) "Cannabaceae", Angiosperm Phylogeny Website, retrieved 2014-02-25
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.
Other than a shared evolutionary origin, members of the family have few common characteristics; some are trees (e.g. Celtis), others are (e.g. Cannabis).
Leaves are often more or less palmately lobed or palmately compound and always bear . are always present and some members of this family possess .
Cannabaceae are often dioecious (distinct male and female plants). The flowers are actinomorphic (radially symmetrical) and not showy, as these plants are wind pollination. 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 , while the female ones are shorter and bear fewer flowers. The pistil is made of two connate , the usually superior ovary is unilocular; there is no fixed number of .
The fruit can be an achene or a drupe.
Modern molecular phylogenetics suggest the following relationships:
Humulus lupulus, the common hop, has been the predominant bittering agent of beer for hundreds of years. The flowers' resins are responsible for beer's bitterness and their ability to extend shelf life due to some antimicrobial qualities. The young shoots can be used as a vegetable.
Some plants in the genus Cannabis are cultivated as hemp for the production of fiber, as a source of cheap hemp oil, for their nutritious seeds, or their edible leaves. Others are cultivated for medical or recreational use as dried flowers, Hashish, or Cannabis edible. Induced parthenocarpy in pistilate flowers, and cannabis strains are used to produce either higher or lower yields of tetrahydrocannabinol (THC), other , as well as terpenes with desired flavors or aromas, such as blueberry, strawberry, or even citrus.
Many trees in the genus Celtis are grown for landscaping and ornamental purposes, and the bark of Pteroceltis is used to produce high-end Chinese paper.
Uses
Carbon dating has revealed that these plants may have been used for ritual/medicinal purposes in Xinjiang, China as early as 494 B.C.
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