Plants perennial; stoloniferous. Culms 10-40 cm, often decumbent and rooting at the lower nodes. Leaves not aromatic; ligules membranous, ciliate or fimbriate. Inflorescences terminal, solitary rames, spikelets in homomorphic sessile-pedicellate triplets of 2 sessile spikelets and 1 pedicellate spikelet; internodes without a median translucent line; disarticulation in the rames below the sessile spikelets, sometimes also beneath the pedicellate spikelets. Spikelets dorsally compressed, with 1 floret; sessile spikelets bisexual; pedicellate spikelets bisexual, unisexual, or sterile. Glumes equal, oblong, truncate, membranous; lower glumes with the margins incurved over the upper glumes; upper glumes keeled; florets bisexual; lemmas hyaline, bifid almost to the base, awned from the cleft; awns twisted, geniculate; anthers 3. Pedicels not fused to the rame axes. x = 10. Name from the Greek polys, many, and trias, in threes, a reference to the large number and unusual arrangement of the spikelet triads.

Polytrias is a monotypic genus of the Asian tropics that has become naturalized in Africa and the Western Hemisphere. It is unusual within the Andropogoneae in having only one floret, rather than two, in its spikelets.

1.   Polytrias amaura (Büse) Kuntze
Java Grass

Plants highly stoloniferous. Culms 10-40 cm, decumbent, rooting at the lower nodes, erect portions 10-20 cm; nodes pubescent; internodes glabrous. Leaves cauline, often purplish; sheaths keeled, pubescent basally and sometimes sparsely so distally, margins ciliate; ligules 0.2-0.5 mm, truncate; blades 0.5-7 cm long, 1-7 mm wide, flat, pubescent. Rames 2-3 cm; internodes 2-3 mm, flat, ciliate on the edges and distally. Sessile spikelets 3-4 mm, ovate, pilose, brown or yellow-brown; calluses blunt; glumes concealing the floret; lower glumes 2-3 mm; lemmas about 1 mm; awns 4-12 mm, exserted, geniculate, twisted below the bend, brown. Pedicels 4-4.5 mm, slender, free of the rame axes. Pedicellate spikelets similar to the sessile spikelets or somewhat smaller, sometimes staminate. Caryopses 1.5-1.8 mm. 2n = 20.

Polytrias amaura is native to southeastern Asia. It used as a lawn grass in tropical and subtropical regions, including Florida. It gives a purplish cast to a lawn.