Agavaceae is a family of plants. Many of these plants grow in dry, hot climates. Some grow in the desert. Well-known plants of this family are the agave, yucca, and Joshua tree. The family includes about 550-600 species in around 18 genera. It is widespread in the tropical, subtropical and warm temperate regions of the world.
It is not quite clear how large the family really is. There are genera which some biologists leave out of the family. This includes for example Cordyline and Dracaena, which are sometimes separated off into a separate family, Dracaenaceae. Recent research has tended to incorporate these into a larger family Ruscaceae, though. 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 are Chlorogalum, Camassia and the family Anthericaceae. This would enlarge the family with anything up to 22 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. 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).
Some species are succulent. In general, Agavaceae leaves occur as rosettes at the end of a woody stem, which may range from extremely short to tree-like heights, as in the Joshua tree. The leaves are parallel-veined, and usually appear long and pointed, often with a hardened spine on the end, and sometimes with additional spines along the margins.
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References[change | change source]
- D. J. Bogler, J. C. Pires and J. Francisco-Ortega (2006). "Phylogeny of Agavaceae based on ndhF, rbcL, and its sequences: implications of molecular data for classification". Aliso 22: 313–328.
- David J. Bogler and Beryl B. Simpson (1995). "A Chloroplast DNA Study of the Agavaceae". Systematic Botany 20: 191–205. http://links.jstor.org/sici?sici=0363-6445%28199504%2F06%2920%3A2%3C191%3AACDSOT%3E2.0.CO%3B2-L.
- David J. Bogler and Beryl B. Simpson (1996). "Phylogeny of Agavaceae Based on ITS rDNA Sequence Variation". American Journal of Botany 83: 1225–1235. http://links.jstor.org/sici?sici=0002-9122%28199609%2983%3A9%3C1225%3APOABOI%3E2.0.CO%3B2-6.
- J. C. Pires, I. J. Maureira, J. P. Rebman, G. A. Salazar, L. I. Cabrera, M. F. Fay, and M. W. Chase (2004). "Molecular data confirm the phylogenetic placement of the enigmatic Hesperocallis (Hesperocallidaceae) with Agave". Madroño 51: 307–311.