New species of bee-pollinated Castilleja from Peru, with a taxonomic revision of South American members of subg. Colacus

A systematic revision of the South American members of Castilleja subg. Colacus based on evidence from floral morphology, SEM of seeds, chromosome numbers, and geographic distribution is presented, recognizing seven species. Four annual species, Castilleja alpicola, C. peruviana, C. profunda, and C. vadosa, all in the annual sect. Oncorhynchus, are described as new with a discussion on their systematic relationships. A key to species is provided and each species is illustrated with line drawings; distribution maps and citations of all known collections indicate sites of known populations. The five known chromosome counts, four of n = 36 (hexaploid) and one of n = 48 (octoploid), suggest that polyploidy has played a major role in the evolution of South American Castilleja subg. Colacus. The introduction of self-compatible C. attenuata into central Chile is postulated to have taken place relatively recently from the western United States