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.

Perennials, Terrestrial, not aquatic, Stolons or runners present, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes solid or spongy, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or lo ose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades lanceolate, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Ligule present, Ligule a fringed, ciliate, or lobed membrane, Inflorescence terminal, Inflorescence a dense slender spike-like panicle or raceme, branches contracted, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence single raceme, fascicle or spike, Inflorescence spikelets arranged in a terminal bilateral spike, Flowers bisexual, Spikelets sessile or subsessile, Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets solitary at rachis nodes, Spikelets distichously arranged, Spikelets all alike and fertille, Spikelets bisexual, Inflorescence disarticulating between nodes or joints of rachis, rachis fragmenting, Spikelets falling with parts of disarticulating rachis or pedicel, Spikelets closely appressed or embedded in concave portions of axis, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 1 clearly present, the other greatly reduced or absent, Glumes distinctly unequal, Glumes equal to or longer than adjacent lemma, Glumes awned, awn 1-5 mm or longer, Glumes 4-7 nerved, Glumes 8-15 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma 3 nerved, Lemma body or surface hairy, Lemma apex truncate, rounded, or obtuse, Lemma awnless, Lemma straight, Palea present, well developed, Palea membranous, hyaline, Palea shorter than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.