Xenophyllum, a New Andean Genus Extracted from Werneria s.l. (Compositae: Senecioneae)

A new genus, Xenophyllum, is de- scribed, which consists of 21 species extracted from Wernena s.l. (Compositae: Senecioneae). All members of this new genus are mat- or hummock-forming pe- rennials that grow at high elevations (3000-5200 m) in the Andes from Colombia to northern Argentina and northern Chile. Included is a brief description of the disposition of the species of Wernena s.l. and a preliminary key to those included in Xenophyllum. Wernena s.l. is a genus of 40 50 species that grows in the high-elevation areas of the Western Hemi- sphere. All but one of the species are confined to the Andes and can be found from Merida, Venezuela, to Patagonia. The one exception is W. nubigena, which is primarily South American but also has a few iso- lated populations in Mexico and northern Guatemala. The species historically included in Wernena s.l. are related to Senecio L. and its relatives. The character that is most frequently used to circumscribe Wernena s.l. is the connate fusion of the involucral bracts at least halfway up from the receptacle (Blake, 1928; Humboldt et al., 1820; Rockhausen, 1939; Weddell, 1856). However, the fusion of the involucral bracts varies a great deal; sometimes they are fused less than half their length in many of the species of Wernena s.l., and more than halfway in some members of Se- necio. Also important is the fact that the fusion is partially a function of the maturity of the head, with some involucral bracts being fused at the base but splitting in late flowering or fruiting stages. One char- acter that is consistent in Werneria s.l. is the lack of a calyoulus; however, there are members of Senecio and related genera that lack a calyoulus. Finally, all but three of the species have white ray florets (two have yellow and one has purple); all three colors are known in Senecio. Although Werneria s.l. is probably not monophy- letic, there are at least three identifiable groups within the genus that can be recognized as distinct genera. The first group consists of rosette-forming plants that are solitary or in small clumps. This group has 2F 30 species and contains the type species, Werneria nubigena Kunth, and can now be referred to as Wer- nena s. str. A second group, the new genus Misbroo- kea V. A. Funk, is monotypic, with M. stngossima (A. Gray) V. A. Funk being its only member (Funk, 1997). The third group contains 21 species that form loose or tightly compressed hummocks or well-developed mats and have leaves along the rhizomes; these spe- cies are here moved into a new genus, Xenophyllum V. A. Funk.