Carex concava ( Carex sect. Rhomboidales , Cyperaceae), a new species from Hainan, China

A new species of Carex sect. Rhomboidales , Carex concava , is described and illustrated from Hainan, China. The new species is similar to C. paracheniana but differs in having wider blades and longer sheaths of bracts; inflorescence with 3 spikes; terminal spike 2–6 cm long and with a 4–14 cm long peduncle; lateral spikes 3–6 cm long, loosely flowered and with 8–15 cm long peduncles; staminate glume ovate, 1-veined costa excurrent into a shortly awn ca. 0.3 mm; pistillate glume ovate, ca. 4 mm long, 1-veined costa excurrent into a awn ca. 1 mm; perigynia fusiform and green; nutlets inclined-oval, brownish black, with 3 angles deeply constricted at the middle and the side toward of spike-stalk deeply concave at base.