The Taxonomy of the Carex bicknellii Group (Cyperaceae) and New Species for Central North America

Abstract

Based on morphology and karyology, we found the eastern North American species Carex bicknellii (sect. Ovales) to be a complex of four spe- cies. We describe two new species, C. missouriensis and C. shinnersii, and raise one variety, C. bicknellii var. opaca, to species rank as C. opaca. The three species segregated from C. bicknellii have lower chromosome numbers: n = 23 II + 1 III to 27 II for C. missouriensis, n = 29 II + 1 III to 30 II for C. shinnersii, and n = 32 II + 1 III to 34 II for C. opaca. All three species are characterized by large tussocks, herbaceous textured foliage and smooth sheaths, and long apiculum on the achenes; they occupy hydric habitats. Carex missouriensis, a spe- cies characterized by awned pistillate scales, grows in remnant prairie swales from western Indiana to southeastern Nebraska. Carex opaca, with blunt scales and large perigynia, has a narrow distribu- tion mostly limited to the periphery of the Ozark Mountain system. Carex shinnersii, with acuminate but unawned scales and perigynia smaller than C. opaca and C. missouriensis, ranges from northern Texas to southern Kansas. This last species is also contrasted with C. brevior, a species with similar morphology and overlapping range. Carex bicknellii in the strict sense is morphologically similar to the northeastern species C. merritt-fernaldii. They both have few culms per tussock, coriaceous foliage with papillose sheaths, papery, erose-margined perigyn- ia, achenes with a very short apiculum, and rela- tively high chromosome numbers (n = 35 II to 39 II). These two species differ in characters of the anther, achene, and perigynium. They occupy more or less xeric habitats, especially in the Central Plains of the United States (C. bicknellii) and south- ern Canada eastward from the Great Lakes region