日本刺子莞 ri ben ci zi guan

Rhynchospora nipponica Makino.

Perennials. Rhizomes short, creeping. Culms erect, simple, 60-100 cm tall, rigid, with several nodes, smooth, basally obtusely 3-angled and clothed with dusky brown bladeless sheaths, apically acutely 3-angled. Leaves longer than culm; sheath elongated, tightly surrounding culm; ligule rust-colored brown, short, membranous; leaf blade broadly linear, 5-9 mm wide, flattish, apex long acuminate to acute. Involucral bracts spreading, 7-20 cm, much longer than inflorescence, sheathless. Inflorescences spicate, 3-20 cm, with 2-7 heads, basally interrupted, apically subcontiguous; heads sessile, globose, 1-1.5 cm in diam. Spikelets narrowly ovoid, 6-7 mm, weakly laterally compressed, 1-flowered, base contracted, apex acuminate. Glumes 5 or 6; basal 3 or 4 grayish brown, ovate, much smaller than others, membranous, 1-veined, apex acute; apical 2 glumes lanceolate-ovate. Perianth bristles 6, filiform, 3.5-4.5 mm, ca. 2 × as long as nutlet, flexuose, smooth. Stamens 3; anthers ca. 2 mm. Style slender; stigmas 2. Nutlet dark brown, obovoid to broadly obovoid, 2-2.3 mm, biconvex, indistinctly transversely wrinkled, shiny, base attenuate; persistent style base narrowly conic-subulate, 4-5 mm, glabrous. Fl. and fr. Sep-Oct.

Swamps, rarely in shallow water. Guangdong, Taiwan [Indonesia, Japan, Korea, Malaysia].