Carex subg. Vignea is characterized by sessile bisexual spikes, distigmatic flowers, and the lack of cladoprophylls. Phylogenies reconstructed using nrDNA internal and external transcribed spacer (ITS and ETS 1f) sequences for 100 vignean taxa support this subgenus as monophyletic. The atypical C. gibba is sister to all remaining taxa. Many clades in the remainder of the subgenus do not correspond to easily defined morphological groups, with species representative of several disparate sections frequently contained within a single clade. Many traditionally recognized sections are not supported, although others such as sects. Ovales, Stellulatae, and Glareosae are monophyletic. Tree topologies indicate that gynaecandry has evolved multiple times in subg. Vignea. Species of uncertain subgeneric affinity are variously placed in our analysis. Carex fecunda, previously linked to subg. Vignea, is positioned within the outgroup composed of species traditionally placed in subg. Carex and Vigneastra. While species with highly compound inflorescences are often regarded as ancestral in Carex, our results indicate that this inflorescence type has evolved multiple times and is derived within subg. Vignea.