Cannabis - Hemp
Humulus - Hop
Trema - Trema
Cannabaceae is a small family of flowering plants.
According to the Royal Botanical Gardens database, there are 170 species grouped in nine to fifteen genera, including three well-known genera Cannabis (hemp), Humulus (hops) and Celtis (hackberries). Celtis is by far the largest genus, counting 60-70 species. However Celtis is sometimes considered to be in a sister family, Celtidaceae.
Cannabaceae used to be part of the order Urticales, which is now included into Rosales. The family is closely allied with the other families of the old Urticales, Moraceae, Urticaceae, and Ulmaceae. The old Urticales are sister to the rest of Rosales.
Celtis is peculiar among Cannabaceae, as it is a tall tree and it is not dioecious. It was previously included either in the strictly related family Ulmaceae (the elm family) or their own family the Celtidaceae, and has been recently included into Cannabaceae by the Angiosperm Phylogeny Group after genetic analysis.
Cannabaceae are very similar to Moraceae. Members of this family can be trees (e.g. Celtis), erect (e.g. Cannabis), or twining herbs (e.g. Humulus).
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 is short and there is no corolla. Flowers are grouped to form cymes. In the dioecious plants the masculine inflorescences are long and look like panicles, while the feminine are shorter and bear less flowers. The pistil is made of two connate carpels, the usually superior ovary is unilocular; there is no fixed number of stamens.
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