Morphological, geographical, and ecological differentiation in the Carex Willdenowii complex (Cyperaceae)

Field studies as well as principal components analysis and analyses of variance of specimen measurements revealed morphologic variation within Carex willdenowii correlated with differences in geographical distribution and habitat characteristics. C. willdenowii is actually a complex of three species, C. basiantha Steudel, C. willdenowii Willdenow, and C. superata Naczi, Reznicek, & B.A. Ford, sp. nov. Carex basiantha is a calciphile of moist forests in the southern United States. It has relatively long culms and terminal spikes with long staminate portions. Carex willdenowii is a calcifuge of dry forests in the northeastern United States and immediately adjacent Canada. It has relatively long culms and terminal spikes with short staminate portions. Carex superata is a facultative calciphile of moist to dry forests of the southeastern United States. It has relatively short culms and terminal spikes with long staminate portions. Synonymies, typifications, descriptions, and citations of representative specimens are provided for each species, along with an identification key. The recognition of previously unsuspected diversity in a species from a region with a relatively well-known flora suggests the systematics of other common, widespread, and morphologically divergent species should be investigated. Carex section Phyllostachys (J. Carey) L.H. Bailey is a small and morphologically distinctive group of sedges endemic to North American forests and forest openings. In the most recent taxonomic study of the section, Catling, Reznicek, and Crins (1993) included six species: C. backii Boott; C. jamesii Schwein.; C. juniperorum Catling, Reznicek, & Crins; C. latebracteata Waterf.; C. saximontana Mack.; and C. willdenowii Willd. Members of the section possess winged culms and peduncles, both of which are dilated at their apices; androgynous spikes, with the lateral ones (lacking in C. latebracteata) arising from the base of the plant on capillary peduncles; large and often leaf-like scales subtending at least the lower perigynia in each spike; and beaked perigynia with entire orifices. At least some of these features are probably autapomorphies diagnosing a monophyletic section, though the polarization of character states is a very uncertain and difficult endeavor in a genus so large ( ;2000 species)