Agavoideae is a subfamily of monocot flowering plants in the family Asparagaceae, order Asparagales. It has previously been treated as a separate family, Agavaceae. The group includes many well-known desert and dry zone types such as the agave, yucca, and Joshua tree. There are about 640 species in around 23 genera, widespread in the tropical, subtropical and warm temperate regions of the world.
Description and uses
Species may be succulent or not. In general, Agavoideae 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.
The taxonomy of the group has varied widely. In the APG III system of 2009, adopted here, the Agavoideae is defined very broadly to include the former family Agavaceae along with other formerly separate families such as Anemarrhenaceae, Chlorogalaceae, Hostaceae, Yuccaceae, Anthericaceae, Hesperocallideaceae and Chlorogalaceae. This is based on data from molecular systematics. Stevens comments that "The broad concept of Agavoideae [...] may not seem very satisfactory" but that none of the alternatives is better. Sources prior to 2009 will still have Agavaceae (in varying circumscriptions) as a separate family and may contain varying numbers of other families included in Agavoideae in the APG III system.
Some genera formerly placed in this group (under whatever name) have been separated off; e.g. Dracaena, which superficially resembles some species of Agave, is currently placed in the subfamily Nolinoideae.
A possibly partial list of the genera included in the Agavoideae is given below, based on Chase et al. (2009) and Stevens. As noted above, the genera currently included in this subfamily have varied widely in their limits and assignment to families and subfamilies; some former family placements other than Agavaceae which will be found in the literature are given below.
|Genus||Former family placement(s) outside Agavaceae/Agavoideae|
|Behnia Didr.||Behniaceae, Philesiaceae|
|Camassia Lindl., nom. cons.||Chlorogalaceae, Hyacinthaceae|
|Chlorogalum (Lindl.) Kunth||Chlorogalaceae, Hyacinthaceae|
|Chlorophytum Ker Gawl.||Anthericaceae|
|Hastingsia S.Watson||Chlorogalaceae, Hyacinthaceae|
|Herreria Ruiz & Pav.||Herreriaceae|
|Hesperocallis A.Gray||Hesperocallidaceae, Hyacinthaceae|
included in Yucca by some sources)
|Leucocrinum Nutt. ex A.Gray||Anthericaceae|
included in Agave by some sources)
|Paradisea Mazzuc., nom. cons.||Asphodelaceae|
included in Agave by some sources)
|Schoenolirion Torr., nom. cons.||Chlorogalaceae, Hyacinthaceae|
|Yucca L. (including Samuela)||Yuccaceae|
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- ^ a b c Chase, M.W.; Reveal, J.L. & Fay, M.F. (2009), "A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae and Xanthorrhoeaceae", Botanical Journal of the Linnean Society 161 (2): 132–136, doi:10.1111/j.1095-8339.2009.00999.x
- ^ a b c d Stevens, P.F. (2001 onwards), Angiosperm Phylogeny Website: Asparagales: Agavoideae, http://www.mobot.org/mobot/research/apweb/orders/asparagalesweb.htm#Agavaceae, retrieved 2011-05-17
- ^ Angiosperm Phylogeny Group (2009), "An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III", Botanical Journal of the Linnean Society 161 (2): 105–121, doi:10.1111/j.1095-8339.2009.00996.x, http://www3.interscience.wiley.com/journal/122630309/abstract, retrieved 2010–12–10
- ^ Vascular Plant Families and Genera, Royal Botanic Gardens, Kew, http://data.kew.org/vpfg1992/vascplnt.html, retrieved 2011-05-17
- David J. Bogler, J. Chris Pires and Javier Francisco-Ortega (2006). "Phylogeny of Agavaceae based on ndhF, rbcL, and ITS sequences: implications of molecular data for classification". Aliso 22 (Monocots: Comparative Biology and Evolution): 313–328.
- David J. Bogler and Beryl B. Simpson (1995). "A Chloroplast DNA Study of the Agavaceae". Systematic Botany 20 (2): 191–205. doi:10.2307/2419449. JSTOR 2419449.
- David J. Bogler and Beryl B. Simpson (September 1996). "Phylogeny of Agavaceae Based on ITS rDNA Sequence Variation". American Journal of Botany 83 (9): 1225–1235. doi:10.2307/2446206. JSTOR 2446206.
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