Pacific Island Thintail

Culm long creeping. Blade about 20 cm long by 5 mm wide, subulate; ligule about 0.8 mm long, chartaceous, truncate and minutely ciliate on backside. Inflorescence a spike; spikelets sunken in a cavity of the rachis joint. Spikelets 2-flowered, about 12 mm long; rachis joints about 4 mm long; lower glume deltoid, membranous; margins minutely scabrid, about 0.8 mm long; upper glume coriaceous, about 12 mm long, lanceolate, aristate, margins membranous and inrolled; lemma subcoriaceous, about 4.5 mm long, broadly lanceolate, 3-nerved, lateral nerves close to margin, acute, basal part minutely bearded; palea elliptical, subcoriaceous, as long as the lemma; anther about 2 mm long. Caryopsis about 6 mm long, oblong; embryo 1/2 the length of the caryopsis.

Perennial, stoloniferous, often very widely spreading. Culms tough, 20–50 cm tall, much branched. Leaf sheaths usually keeled, glabrous; leaf blades stiff, flat or involute, glaucous, 3–20 cm, 2.5–5 mm wide, glabrous or adaxially pilose near ligule, margins scabrous, apex acuminate; ligule 0.3–0.8 mm. Raceme erect, 5–15 cm; spikelets sometimes paired on each internode toward raceme base; rachis scabrous-hispidulous, internodes 3–5 mm. Spikelets 10–12 mm, florets often 2; lower glume membranous, triangular, up to 0.8 mm or absent; upper glume narrowly lanceolate, as long as spikelet, leathery, scabrous, apex caudate-aristate; lower lemma broadly lanceolate, 3.7–4.5 mm, puberulous near base, cartilaginous in lower two-thirds, thinner and scabrous above, apex acute. Anthers 1.5–2 mm. Caryopsis strongly dorsally compressed, plano-convex, 1.6–2 mm. 2n = 54.

Distributed along the coasts of Ceylon, Kenya, Mascarenes to Taiwan and Australia.

Rocky and sandy seashores, especially coral sand. Taiwan [Japan (Ryukyu Islands), Indonesia, Malaysia, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam; E Africa, N Australia, Indian Ocean Islands, Pacific Islands (Polynesia)].

Rottboellia repens G. Forster, Fl. Ins. Austr. 9. 1786; Mon-erma repens (G. Forster) P. Beauvois.