Taxonomy of the Carex backii complex (section Phyllostachyae, Cyperaceae)

A combination of macro- and micromorphological, anatomical, and phytogeographical data supports the recognition of three species in the Carex backii complex (within sect. Phyllostachyae). Carex backii is widely distributed throughout temperate and boreal regions of North America and is easily recognized by its long, smooth surfaced perigynia (4.8-6.6 mm) with long beaks (1.9-2.9 mm). The leaves are dull green to yellow-green with green, crenate margins. Carex saximontana is confined to the Great Plains region of North America and is distinguished by its shorter, papillose perigynia (3.2-4.9 mm) with much shorter beaks (0.6-1.2 mm). In addition, die leaves are greenish-glaucous to dark herbage-green with distinctive hyaline margins. Carex cordillerana occurs from central British Columbia to central Utah and is described as a widespread new species. Carcx cordillerana can be recognized by its dull green to yellow-green leaves with green margins that are densely covered in papillae. Perigynia are intermediate in size between C. saximontana and C. backii (3.9-5.4 mm), but have a unique epidermal cell morphology. Perigynium beaks are similar in length to those found in C, saximontana (0.5-1.6 mm). The North American Carex flora has proven to be a rich source of taxonomic novelties over the past 20 years. This is nowhere better exemplified than in Carex sect. Phyllostachyae.