A phylogenetic reconstruction of Antennaria (Asteraceae: Inuleae)

Abstract

A cladistic analysis of 32 sexually reproducing species of Antennaria Gaertn. revealed that the genus comprises five constitutive monophyletic groups: Geyeriae, Argenteae, Dimorphae, Pulcherrimae, and Catipes. Three of the groups, Argenteae, Dimorphae, and Geyeriae, have retained relatively large numbers of plesiomorphic characters. The members of these three groups are mostly nonstoloniferous and have not evolved characters often associated with sexual dimorphism that occur in the remainder of Antennaria. Consequently these three groups closely resemble the suprageneric outgroup, Anaphalis and Gnaphalium. The Pulcherrimae and Catipes represent the most specialized groups. These two groups have wider distributions and occur in a much greater diversity of habitats than the Argenteae, Dimorphae, and Geyeriae. Evolutionary advancement in the genus has been toward dioecism and coincident sexual dimorphism, probably as a method to promote outcrossing. In addition, polyploidy and two asexual means of reproduction, agamospermy and horizontal stolons, have evolved in the more specialized groups, the Pulcherrimae and Catipes. Antennaria probably arose from Mexican Gnaphalium sometime during the Oligocene or Miocene, migrated into the western United States where it has evolved and migrated into other areas of the northern hemisphere and South America. Key words: Antennaria, Asteraceae, Inuleae, cladistics phylogeny, biogeography.