Since the early 19th century, there has been considerable confusion concerning the proper delimitation of the genus Cymopterus (Apiaceae; Umbelliferae) and its relationship to putatively allied genera Aletes, Harbouria, Lomatium, Musineon, Neoparrya, Orogenia, Pteryxia, and Shoshonea. Regarding Cymopterus, extremes in treatment range from the recognition of many generically distinct elements (such as, Pseudocymopterus, Podistera, Oreoxis, Pteryxia, and Glehnia) to one large genus with multiple subgenera and sections. Currently, some 35 species are recognized within Cymopterus. These plants are largely endemic to western North America. They are all herbaceous perennials, frequently caespitose and xerophytic in habit, and usually occur in elevated habitats. Our major goal is to produce an explicit phylogenetic hypothesis for Cymopterus using anatomical, morphological, and molecular evidence. To date, we have obtained sequence data from the nuclear rDNA ITS region as well as the chloroplast rps16 intron, trnL intron, and the trnF-trnL-trnT intergenic spacer regions. Anatomical and morphological data have also been procured, with emphasis placed on the taxonomically problematic species Pseudocymopterus montanus, Pteryxia terebinthina, and Cymopterus acaulis. While our results are preliminary, the molecular data suggest that Aletes, Cymopterus, Lomatium, Musineon, and Oreoxis are each not monophyletic, as currently circumscribed. The analyses of morphological data suggest that Pseudocymopterus montanus cannot be divided into infraspecific taxa. Moreover, the separation of Pteryxia terebinthina varieties albiflora and californica, and the separation of Cymopterus acaulis varieties acaulis and fendleri, are not supported.

Key words: Apiaceae, Cymopterus, ITS, rps16, trnF-trnL-trnT, Umbelliferae