Agavaceae is a
family of
plants that includes many well-known
desert and dry zone types such as the
agave,
yucca, and
Joshua tree. The family includes about 550-600
species in around 18
genera, and is widespread in the tropical, subtropical and warm temperate regions of the world.The circumscription of this family has varied widely. Some genera (e.g.
Cordyline and
Dracaena) are sometimes separated off into a separate family,
Dracaenaceae, though recent research has tended to incorporate these into a larger family
Ruscaceae. Nolina, Beaucarnea, and Dasylirion are sometimes recognized as Nolinaceae or placed in Ruscaceae. Conversely, data from
molecular systematics now suggest that Agavaceae should be broadened to include a number of genera previously classified elsewhere, among them
Chlorogalum,
Camassia and the family
Anthericaceae with anything up to 22 additional genera. The
Angiosperm Phylogeny Group's APG II classification places Agavaceae, along with a number of other families (including Ruscaceae) in an expanded family
Asparagaceae. However, APG II allows the alternative of keeping some of these families, including Agavaceae, separate, though in this case it recommends expanding the family to include the genera currently classified in
Anemarrhenaceae,
Anthericaceae (with Anthericum and Paradisea),
Behniaceae and
Herreriaceae. Most references have retained Agavaceae (in varying circumscriptions) as a family distinct from Asparagaceae.
Hesperocallis, sometimes placed in its own family, Hesperocallideaceae, has recently been shown to be closely related and its inclusion in Agavaceae has been recommended (Pires et al. 2004).
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