Themeda quadrivalvis

Veldkamp, J. F., 2016, A revision of Themeda (Gramineae) in Malesia with a new species from Laos, Blumea 61 (1), pp. 29-40 : 34-35

6. Themeda quadrivalvis (L.) Kuntze

Themeda quadrivalvis (L.) Kuntze (1891) 794. — Andropogon nutans L. (1771) 303,non L. (1753). — Andropogon quadrivalvis L. (1774) 758,corr. pro L. (1771). — Anthistiria ciliata L.f. (1782 ‘1781’) 113; Retz. (1783) 11; Andersson (1856) 237 (‘Retz.’), incl. var. ciliata , nom.superfl. — Themeda ciliata (L.f.) Hack. in Duthie (1888) 89; Hack. (1889) 664, nom. superfl. — [ Themeda ciliata (L.f.) Hack. subsp. genuina A. Camus (1920b) 423, nom. inval.]. — [ Themeda arguens (L.) Hack. var. ciliata (L.f.) Roberty (1954) 411,comb.inval.:no basion., not in Boissiera 9 (1960)]. — Lectotype: Herb. Linn. 1211.5 (LINN, microfiche IDC; S), designated by Cope (2000: 246).

? Anthistiria barbata auct. non Desf.: Desf. (1792) 294, t. 2, pro descr., illus. — Voucher:? Jos.Martin in Herb. Thouin s.n. (possibly in G-DEL,MPU, P).

Plants annual (sometimes long-living). Culms 0.1–2 or more m long, tufted. Nodes glabrous. Ligule 1–3 mm long, margin glabrous to ciliolate. Leaves 15–35 cm by 2–6 mm.Uppermost spatheoles glabrous. Peduncle 0.5–3 mm long, extremely short, glabrous. Capitule long-persistent. Involucral spikelets conspicuous, pairs inserted at the same level, sterile or male; lower glumes oblong to lanceolate, 4–7 by c. 1.5 mm, acute or abruptly obliquely apiculate, herbaceous, 9- or 11-nerved, distally or dorsally with bulbous based bristles; upper glumes 3-nerved. Fertile spikelets 1, 4–6 mm long (incl. callus), callus 0.5–1 mm long, hairs brown, 1.7–2.5 mm long; lower glumes brown to castaneous, apex truncate, surface smooth, puberulous or distally hispidulous. Awn well-developed, perfect, 30– 50 mm long, column 13–21 mm long (i.s.), geniculate, hairs white (i.s.). Anthers 1.3–3 mm long, purple, orange, or yellow i.s. Pedicel glabrous. Pedicelled spikelets 2, sterile or male, 4–7 mm long, lower glumes apex acuminate to aristate, glabrous. 2n = c. 40.

Distribution — Sikkim, CE India (East from Madhya Pradesh) to S China; Thailand (Northern: Kamphaeng Phet). In view of the large disjunction in distribution, I suspect introduction also in Malesia: Lesser Sunda Isl. (Sumba, Timor). Reported for Papua New Guinea ( Lazarides 1980, but no specimens seen, not in Henty 1969). Sometimes introduced at an early date elsewhere in pasture seed, birdseed, hay, etc. Argentine, N Australia, Cuba, Dominican Republic, Guadeloupe, Fiji, Iraq, Lebanon, Madagascar, Mauritius (Île de France, e.g. Sieber 1821–1823,? Joseph Martin for Thouin 1788), New Caledonia, Réunion (‘Bourbon’, e.g. Boivin 1846–1852), Seychelles, Socotra, USA (e.g. California, Florida, Kansas, Louisiana), etc. Reported for Pakistan, but not there ( Cope 1982: 316).

Habitat — Savannah, grasslands (where it can form dense monocultures), roadsides, gardens, sugarcane fields, orchards, fire resistant, from dry ( 375 mm /a) to wet ( 4500 mm /a) areas, favouring soils with medium-textured surfaces (sandy), 200– 600 m altitude.

Uses — Used as a minor fodder grass, in birdseed mixtures (Towne & Barnard 2000). Regarded as a noxious weed in e.g. Australia, as it can outcompete native species, decrease animal productivity (vigorous and low palatability), and increase fire hazards ( Keir & Vogler 2006).

Collector’s notes — Orange red or golden when mature. Panicles reddish, brownish.Spatheoles green, often reddish brown.

Vernacular name — Grader grass, also Habana grass, Kangaroo grass, Oatgrass.

Notes — In some places, e.g. the Levant and possibly elsewhere, confused with T. triandra , whereby the delimitation and distribution is uncertain and needs special attention.

Because T. triandra is so common in Malesia, this species is easily overlooked. The differences are few, but clear and appear to be constant. One would be tempted to regard this as a subspecies or variety of it. I have refrained from doing so here, also because of the economic importance of T. quadrivalvis .