1. Tricostularia undulata (Thwaites) J. Kern, Acta Bot. Neerl. 8: 267. 1959.
三肋果莎 san lei guo suo
Cladium undulatum Thwaites, Enum. Pl. Zeyl. 353. 1864.
Herbs, tussock-forming. Roots thick. Culms 30-90 cm tall, 1-2 mm thick, rigid, obtusely 3-angled, sulcate-striate, smooth. Leaves basal, shorter than to as long as culm; leaf blade 1-3 mm wide, rigid, margin involute and scabrous. Inflorescences paniculate, branched, diffuse to dense, consisting of 4 or 5 fascicles; branches 2 or 3 together, unequal, ± exserted from sheath, compressed, rigid, flexuose, scabrous. Spikelets almost sessile, in clusters of 2-8, 1-flowered. Glumes 4, oblong-lanceolate, apex acute; basal 2 glumes ca. 2 mm, apical ones 4-5 mm. Perianth scales 6, lanceolate to linear-lanceolate, densely covered with white antrorse short hairs. Stamens 3; anthers ca. 2 mm; connective apex 3-sided, oblong. Nutlet chestnut-brown to blackish, obtusely 3-sided, slightly reticulate-rugulose, with 3 whitish ribs, apex hispidulous.
Watersides near seacoast; near sea level. Hainan (Wenchang) [India, Indonesia, Malaysia, Papua New Guinea, Sri Lanka, Thailand, Vietnam; N Australia].