Panicum humile Nees ex Steud., Syn. Pl. Glumac.

14. Panicum humile Nees ex Steud., Syn. Pl. Glumac. 1: 84. 1854.

Holotypus: SRI LANKA: sine loco, s.d., Thwaites 3243 (P [not found]; isotype: B, BO, BR [BR0000005919376] image seen, K [K000245604]!, PDA, US image seen, W [W18890065031, W18890163787] image seen).

= Panicum walense Mez in Bot. Jahrb. Syst. 34: 146. 1904 [as watense]. Holotypus: SENEGAL: Near Wato [Walo], III.1828, Leprieur 52 (B [B100168663] image seen; isotype: P [P00442173]!, US [US00140091]!).

Erect annual, in diffuse tufts, 10–40 cm tall, with glabrous stems and nodes. Leaf sheaths glabrous. Ligule a minute ciliolate lacerate membrane. Leaf blades linear, flat, chartaceous, 3– 15 × 0.3– 0.5 cm, drying yellow-green, glabrous on both sides. Panicles terminal, partly exserted, 10–15 cm long, ovate, effuse, abundant and prominent on the plant, the branches filiform, scabrous, the pedicels 1.5–7 mm long. Spikelets ovate, apically acuminate, 1.7 –2(–2.2) mm long, white to purple, gaping open at maturity. Lower glume c. 3/4 as long as the spikelet, apically long-acuminate, 3-veined, glabrous, separated from the rest of the spikelet by a short internode. Upper glume as long as the spikelet, herbaceous, 5-veined, glabrous. Lower floret barren, with a reduced palea. Lower lemma herbaceous, 5-veined, glabrous. Upper lemma c. 1.5 mm long, shorter than the lower floret, smooth, shiny, pale.

Distribution and ecology. – Widespread tropical African and Asian species. Occasional across Madagascar, most commonly recorded from the northwest; near water, below 1000 m (Fig. 8B).

Notes. – The distribution along roads and populated places suggests a non-native origin for this species in Madagascar.

This species is illustrated in BOSSER (1969: Fig. 125f-i as “ Panicum walense ”).

Additional material examined. – MADAGASCAR. Prov. Antsiranana: Nosy Be, Bosser 409 (P [P02608187]); PK 70 Ambilobe – Ambanja, 18.IV.1970, Bosser 20241 (P [P02309343]); Nosy Be, Gaudichaud 191 (P [P02608178]); ibid. loco, Richard 323 (P [P02608177]); ibid. loco, Richard 642 (P [P02608175]). Prov. Mahajanga: Ambalakidy, VI.1953, Bosser 5482 (P [P02608188]); canton de Belobaka, IV.1963, Bosser 17612 (P [P02608182]); canton de Mahazoma, V.1958, Descoings 3408 (P [P02608185]); PK 407 rte Majunga, IV.1967, Morat 2698 (P [P02726844]); Firingalava, III.1898, Perrier de la Bâthie 535 (P [P02608190]); bassin du Bemarivo, X.1906, Perrier de la Bâthie 11129 (P [P02608191]); ibid. loco, III.1907, Perrier de la Bâthie 11141 (P [P02608193]); Majunga, V.1927, Perrier de la Bâthie 17948 (P [P02608186]). Prov.Toamasina: Anororo, W lac Alaotra, VI.1955, Bosser 8139 (P [P02608184]). Prov. Toliara: Manja, 9.IV.1953, Portères s.n. (P [P02307376]).