Phylogeny of the Unispicate Taxa in Cyperaceae Tribe Cariceae II: The Limits of Uncinia

Starr, Julian; Harris, Stephen; Simpson, David

ABSTRACT: Debates on the limits and relationships of Cariceae genera and subgenera have historically focused on a small number of unusual “transitional” taxa and on scenarios involving a reduction or proliferation of rachillae (i.e., spikelet secondary axes). The strongest argument for such theories was provided by Carex microglochin Wahlenb. and Uncinia kingii Boott, a seemingly indisputable link between Carex L. and Uncinia Pers. In this study we examine the limits of Uncinia by focusing on these transitional species and their allies in Carex subg. Psyllophora (Degl.) Peterm., a reduced unispicate group whose species are largely responsible for blurring generic and Carex subgeneric limits. Phylogenies derived from ITS and ETS 1f sequences representing 72 taxa and all five Cariceae genera distinguished four major clades (A, B, C, D), including a predominately unispicate, androgynous clade (A and B) that rejects the classic U. kingii/C. microglochin transition series (i.e., they are polyphyletic). Nonetheless, analyses strongly support a sister relationship between Uncinia s. str. and U. kingii. This is an unexpected result, for strong anatomical and morphological evidence would suggest that U. kingii is closest to C. microglochin and its allies. Moreover, the sister position of U. kingii to Uncinia s. str. suggests that contrary to previous classifications of Uncinia the characters of Uncinia sect. Uncinia are plesiomorphic. This means that despite section Uncinia being largely natural in this analysis, it—like Uncinia s.l.—cannot be defined by any known morphological apomorphy. The implications of the analysis for generic and Carex subgeneric relationships, including the subgeneric and sectional classification of Uncinia, are discussed.