XVI International Botanical Congess
Historical classifications of Eriogonoideae (Polygonaceae) differ in relative inclusiveness of two large genera, Eriogonum and Chorizanthe. This is reflected in the large number of satellite genera currently recognized. Phylogenetic estimates from sequences of the internal transcribed spacer (ITS) of the nuclear ribosomal region, and chloroplast trnL intron and trnL-trnF intergenic spacer show that Eriogonum, Chorizanthe, and Oxytheca as currently circumscribed are not monophyletic groups. These data point to reticulate evolution and/or the use of homoplastic characters in current classifications. The presence of awns, a basis for recognition of Chorizanthe, Oxytheca and various monotypic genera has based upon character reconstruction been gained four times, with as many losses, thus suggesting involucral awns are a very homoplastic character.