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FOC | Family List | FOC Vol. 23 | Cyperaceae

18. Pycreus P. Beauvois, Fl. Oware. 2: 48. 1816.

扁莎属 bian suo shu

Authors: Lun-Kai Dai, Gordon C. Tucker & David A. Simpson

Herbs, annual or perennial. Rhizomes present or absent. Culms usually tufted, 3-angled or compressed 3-angled, rarely triquetrous. Leaves basal, 3-ranked; ligule absent; leaf blade usually present. Involucral bracts (1 or)2-5(-8), leaflike, rarely very thin. Inflorescences terminal, a simple or rarely compound anthela; rays several, long or very short, or inflorescence capitate. Spikelets few to many, arranged into a short spike or capitulum at apex of rays, or fascicled; rachilla not articulate at base, persistent, wingless or narrowly winged. Glumes distichous, gradually deciduous from base to apex of rachilla at maturity, basal 1 or 2 usually without a flower but remaining ones each with a bisexual flower. Flowers without hypogynous bristles or scalelike perianth parts. Stamens 1-3; connective apex prominent or not prominent beyond anthers. Style base not swollen; stigmas 2, deciduous at maturity. Nutlet biconvex, slightly compressed or slightly turgid, one margin facing rachilla, puncticulate and reticulately striate or transversely undulately striate.

More than 70 species: Africa, America, Asia, Europe, oceanic islands; 11 species (three endemic) in China.

1 Cells on nutlet surface transversely oblong with an elevated margin resulting in nutlet surface transversely undulately striate or scabrously rugose   (2)
+ Cells on nutlet surface hexagonally reticulately striate or puncticulate   (4)
2 (1) Culms 10-35 cm tall; spikelets narrowly oblong-ovoid to narrowly linear-ovoid, 0.8-2 cm × 3-3.5 mm, 16-30-flowered; glumes brown to dark brown.   9 P. diaphanus
+ Culms 3-15 cm tall; spikelets ovoid, oblong-ovoid, or narrowly ovoid, 5-15 cm × 2.5-4 mm, 8-16-flowered; glumes straw-colored, yellowish brown, or purplish red   (3)
3 (2) Culms slender; leaves 0.3-1.5 mm wide; anthela rays very short; spikelets 1 to several per ray, nearly fascicled; glumes purplish red to reddish brown on both surfaces.   10 P. setiformis
+ Culms slightly thick; leaves 1-3 mm wide; anthela rays mostly to 2.5 cm; spikelets 3-8 per ray, congested; glumes straw-colored to yellowish brown.   11 P. pseudolatespicatus
4 (1) Glumes broadly sulcate on both surfaces.   8 P. sanguinolentus
+ Glumes not broadly sulcate on both surfaces   (5)
5 (4) Glume apices truncate to emarginate and excurved mucronate to awned.   7 P. pumilus
+ Glume apices obtuse or acute and not excurved mucronate   (6)
6 (5) Spikelets narrowly linear-ovate, narrowly ovoid, narrowly oblong-ovoid, or oblong-ovoid; glumes densely imbricate, ca. 3 mm or more; stamens 3   (7)
+ Spikelets linear, linear-oblong, narrowly linear-ovoid, or narrowly ovoid; glumes slightly laxly imbricate or rarely densely imbricate, 1.5-2 mm; stamens 1 or 2   (8)
7 (6) Spikelets ca. 2.5(-3) mm wide; glumes blackish brown.   1 P. delavayi
+ Spikelets 3-5 mm wide; glumes straw-colored or yellowish brown.   2 P. unioloides
8 (6) Nutlet oblong, both surfaces concave sulcate; stamen 1.   6 P. sulcinux
+ Nutlet obovoid-oblong or obovoid, both surfaces not concave sulcate; stamens (1 or)2   (9)
9 (8) Anthelae with very short rays; spikelets narrowly ovoid to narrowly linear-ovoid; glumes subelliptic, abaxially not conspicuously keeled.   5 P. lijiangensis
+ Anthelae simple, lax, usually with slightly long or rarely very short rays; spikelets linear-oblong or linear; glumes oblong-ovate or subovate, abaxially keeled   (10)
10 (9) Spikelets radiately arranged; rachilla 4-angled, with trabeculae in both lateral sulculi; glumes brown to dark brown, laxly imbricate, apex obtuse; anthers oblong.   3 P. flavidus
+ Spikelets suberect; rachilla flexuose, narrowly winged; glumes straw-colored to rarely pale brown, densely imbricate, apex sometimes mucronate; anthers linear.   4 P. polystachyos

  • List of lower taxa


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