KEW BULLETIN 56: 601 - 626 (2001) Molecular and morphological phylogenetic analyses of Themidaceae (Asparagales) J. CHRIS PIRES1'2, MICHAEL F. FAY2, WARREN S. DAVIS3, LARRY HUFFORD3, JOHAN ROVA4, MARK W. CHASE2 & KENNETH J. SYTSMA' Summary. Phylogenetic analyses of morphological characters and plastid DNA sequences of rbcLand trnL-F are presented separately and combined for nine of the 12 genera of Themidaceae and seven genera of related Asparagales. The results from the combined analysis are the most highly resolved and provide strong support for the monophyly of Themidaceae. Within Themidaceae, the Brodiaea complex of western North America is weakly supported and the Milla complex of Mexico is moderately supported as monophyletic. Within the Brodiaea complex, there are three strongly supported novel clades: (1) Brodiaea and Dichelostemma, (2) Triteleia and Bloomeria, and (3) Muilla and Androstephium. Thus, the previously recognised Brodiaea sensu lato (Brodiaea, Dichelostemma and Triteleia) defined by the presence of an extended perianth tube is polyphyletic. INTRODUCTION Themidaceae Salisb. includes Brodiaea Sm., Milla Cav., and ten other lilioid plant genera found in western North and Central America (British Columbia to northern Guatemala) with centres of diversity in California and western Mexico. These genera are geophytic monocots characterised by a perennating corm, one or a few linear foliage leaves and scapose, umbel-like inflorescences. The systematics of Brodiaea and relatives have been debated for over a century (e.g., Wood 1868, Baker 1871, Watson 1879, Greene 1886, MacBride 1918, Jepson 1925, Hoover 1939a). These genera have been previously included in Liliaceae (Cronquist 1981) or Amaryllidaceae (Traub 1972, Niehaus 1971, Keator 1989). More recent classifications have treated this group as tribe Brodiaeeae of Alliaceae on the basis of the umbellate inflorescence and superior ovary, the characters typically used to circumscribe Alliaceae (e.g., Dahlgren et al. 1985). However, studies of rbcL sequence data have shown that this placement is problematic and indicated rather that Brodiaeeae should be treated as a separate family with closer affinities to Hyacinthaceae and Laxmanniaceae, among other families (Fay & Chase 1996). The exclusion of this tribe from Alliaceae is supported by a number of morphological and anatomical characters including rootstock (corms vs. bulbs), inflorescence bracts (three or more vs. usually two), pedicel bracts (generally present vs. generally absent), hollow vs. solid style, and the absence or presence of alliaceous chemistry (Fay & Chase 1996; Rudall, pers. comm.). For these reasons, Fay Accepted for publicationJune 2001. 1 Department of Botany, University of Wisconsin, Madison, Wisconsin 53706, U.S.A. 2 Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3DS, U.K. 3 Department of Biological Sciences, Washington State University, Pullman, Washington 99164, U.S.A. 4 Department of Systematic Botany, G6teborg University, Carl Skottsbergs Gata 22B, S-413 19 G6teborg, Sweden. 601 This content downloaded from 128.104.46.196 on Fri, 6 Feb 2015 14:25:31 PM All use subject to JSTOR Terms and Conditions