Flora of the Hawaiian Islands
Monocotyledon Literature for Cyperus polystachyos
Wagner et al., 1990, 1999; Lorence & Wagner, 2019.
   Cyperaceae -- The Sedge Family Bibliography
      Cyperus polystachyos
General Information
DistributionNative to tropical and subtropical regions worldwide.In the Hawaiian Islands, indigenous to Midway, Ni`ihau, Kaua`i, O`ahu, Moloka`i, Lana`i, Maui, Hawai`i.

Cyperaceae - Cyperus polystachyos

Click here for detailed USGS map by Jonathan Price
Slender, annual or short-lived, perennial herb, tufted with fibrous roots or in favorable conditions developing a short rhizome; culms stiffly erect, (2‒)20‒60 cm tall, trigonous, smooth.
Leaves few, basal, subrigid, much shorter than or longer than the culm; blade linear, 1.5‒4 mm wide, blade weakly plicate, acute; sheath reddish brown.
Inflorescences open, forming a simple or partially compound umbelliform corymb, with 2‒7 rays 2‒6 cm long, or contracted into a headlike cluster 2‒5 cm in diameter, occasionally developing 2‒5 short rays to 5 cm long; involucral bracts 3‒6, spreading, usually the proximal 2‒3 surpassing the inflorescence, the longest one to 30 cm long. Spikelets yellowish brown to pale or dark reddish brown, numerous, crowded, 8‒40-flowered, digitately disposed, linear-lanceolate, strongly flattened, 5‒25 mm long, 1‒1.5(‒2) mm wide, apex acute, rachilla flexuous, not winged; glumes reddish brown, thin, chartaceous, oblong-ovate to lanceolate-ovate, 1.5‒1.8 mm, keel 3-veined, acute, margin narrowly pale and membranous; stamens (1)2, anthers linear; style slender, twice as long as achene, stigmas 2.
Achenes dark brown, oblong-obovate, laterally flattened, biconvex, ca. 1 mm long, the sides minutely puncticulate.
2n = 96, 98.
David Lorence