Carex xueyingiana (Cyperaceae), a new species from Hainan Island, China

A new species of Carex (Cyperaceae), Carex xueyingiana, from section Radicales, is described and illustrated from Hainan Island, China. We analyzed 35 morphological characters using Cluster Analysis and Principal Components Analysis to evaluate the relationships between the new species and the 15 species from the same section occurring in China. The new species is similar to C. chlorocephalula, displaying pubescent rhizomes, leaves densely hispidulous on both surfaces, and slender tufted culms. Carex xueyingiana differs from C. chlorocephalula by the leaves distinctly longer than culms (not equaling these), stems 4-6 mm wide (instead 1-3 mm), bracts sheath-like, 5-6 mm long (instead leaf-like and 2-3.5 cm long), spikes 7-10 mm long (instead 10-15 mm), and perigynium beakless (instead beaked). The new species is only known from Hainan Island and is assessed as Vulnerable (VU DD).