Aldama is a genus of perennial herbaceous flowering plants in the family Asteraceae (order Asterales), native to tropical and subtropical America. The genus was originally described by Pablo de La Llave and Juan Martínez de Lexarza in 1824 to encompass one or two species within the subtribe Helianthinae distinguished by pales that tightly enclosed the cypselae (achenes). Plants in the genus are characterized by a perennial herbaceous growth habit, a pappus typically composed of awns and scales, and a multi-seriate involucre surrounding the flower heads.
The genus was substantially expanded following molecular phylogenetic work by Schilling and Panero in 2002 and 2011. Their analyses of nuclear ITS, ETS, and chloroplast DNA sequences demonstrated that the large genus Viguiera Kunth did not constitute a natural (monophyletic) group. As a result, they proposed splitting Viguiera into at least eleven genera; Aldama was one of the principal recipients of these realigned species and now encompasses approximately 115–118 species. The genus ranges across much of the Americas, from the southwestern United States south through Mexico and Central America into South America, reaching as far as Argentina, Chile, and Brazil.
Etymology
The genus Aldama was first described and published by Pablo de La Llave and Juan Martínez de Lexarza in Novorum Vegetabilium Descriptiones 1: 14 (1824). The name honours a Mexican patron of the botanical sciences; the genus was initially small but was greatly expanded in the early 21st century following molecular reclassification of the former genus Viguiera.
Distribution
Aldama is native to tropical and subtropical America. Its range spans Mexico, Central America (Belize, Guatemala, Honduras, Nicaragua), and much of South America (Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay, Peru, Uruguay, Venezuela), with a northern extension into the southwestern United States in Arizona, New Mexico, and Texas.
Taxonomy Notes
Aldama was originally a small genus within subtribe Helianthinae (family Asteraceae). Following molecular phylogenetic studies by Schilling & Panero (2002, 2011) using nuclear ITS, ETS, and cpDNA markers, the large genus Viguiera Kunth was shown to be polyphyletic and was divided into at least eleven segregate genera. Aldama was re-established and expanded to receive the bulk of these reassigned species, growing from a handful of taxa to approximately 115–118 accepted species. Related segregate genera from the same reclassification include Bahiopsis, Calanticaria, Dendroviguiera, Heliomeris, and Hymenostephium, among others.
