Digitaria didactyla Willd. (1809: 91)

Boonsuk, Boonchuang, Chantaranothai, Pranom & Hodkinson Abstract, Trevor R., 2016, A taxonomic revision of the genus Digitaria (Panicoideae: Poaceae) in mainland Southeast Asia, Phytotaxa 246 (4), pp. 248-280 : 257

6. Digitaria didactyla Willd. (1809: 91) . Type :— MAURITIUS, J.B.G.M. Bory de Saint Vincent s.n. (holotype B! ( BW01646010 ); isotype BM!).

Perennial. Culms compactly tufted with stolons and runners, up to 35 cm high; nodes glabrous, with roots and shoots covered by cataphylls. Sheaths 2–4.5 cm long, glabrous. Ligules 1.2–1.5 mm long. Blades linear, 5–14 cm by 1.5–1.7 mm, chartaceous, both surfaces glabrous to scaberulous, apex acuminate, margin entire. Inflorescences composed of racemes; peduncles glabrous; common axis absent. Racemes 2–4, digitate, longest 3–7 cm long, digitate; rachis triquetrous and winged, 0.3–0.4 mm wide, smooth. Pedicels serrate or sometimes glabrous; abscission truncate. Spikelets binate, homomorphous, lanceolate, 1.9–2.7 by 0.6–0.75 mm; hairs smooth with acute apex. Lower glume acute to bifid, 0.25–0.3 mm long, membranous. Upper glume lanceolate, 1.5–1.8 mm long, chartaceous, apex acuminate, pilose between the nerves and on margins, nerves 3. Lower lemma lanceolate, as long as the spikelet, pubescent between nerves and on margins but with broad glabrous interspaces beside the midnerve, nerves 7, inequidistant. Upper lemma lanceolate, 2.25–2.4 mm long, apex acute, yellowish. Anthers 0.8–1.2 mm long, yellowish brown. Caryopsis not seen.

Distribution: —Tropical S Africa, Madagascar, Mauritius, Bourbon, Réunion, St. Dénis, cultivated and naturalised elsewhere, e.g. India, Sri Lanka, Malaysia, Singapore, Indonesia, Papua New Guinea, Australia.

Selected specimens examined: —PENINSULAR MALAYSIA. Pahang: Cameron Highlands, 25 May 1931, C.F. Symington SF 25931 (KEP, SING). Selangor: Seri Kembangan, 25 September 2006, A.R. Rafidah & W.Y. Chew FRI 51767 (KEP, L).

Ecology: —Open areas, roadsides and lawns; elevation 0–1,800 m.

Conservation status: — Digitaria didactyla has a widespread distribution. It should be classified as LC according to IUCN (2012) criteria.

Note: —The spikelets of D. didactyla are similar to those of D. ciliaris but the species differs in its compact tufted habit and slender culms, few digitate racemes and in the production of stolons with cataphylls at nodes. Henrard (1950) placed D. didactyla in section Sanguinales which was included in section Digitaria by Veldkamp (1973) but Webster (1983) classified this species in section Erianthae because of its tufted habit and its stolons with cataphylls at the nodes.