Billion Dollar Grass

Echinochloa frumentacea is cultivated both for grain and as a forage crop. It is thought to be a cultivated derivative of E. colona that arose in India and perhaps Africa.

Echinochloa frumentacea is cultivated in the hotter parts of Asia and Africa. Yabuno (in Cytologia 27:296-305.1962; and in Jap. J. Bot. 19:277-323.1966) discusses its cytology and regards it as a derivative of Echinochloa colona. These two species are distinct enough in Asia, but in Africa, where Echinochloa frumentacea occurs spontaneously, they intergrade with one another and are separated rather arbitrarily according to the density of the inflorescence.

Annuals; culms stout, to 10 mm in diam., less than 120 cm high. Blades linear, acuminate, scabrous, 10-40 cm long, 10-20 mm wide, margins cartilaginous, white; ligule absent; sheath glabrous, loose, shorter than internode. Panicle erect, main axis ridged, stout, ridges scabrid, tubercle bristled; branches curved, densely flowered. Spikelets usually purplish, broadly ovate, 3-4 mm long, awnless or sometimes mucronate; lower glume small, 1/3-3/5 as long as spikelet; upper glume slightly shorter than spikelet, usually awn-tipped, lower lemma staminate; upper floret protruding above glumes when mature, mucronate, smooth and shining, margins inrolled, enveloping upper palea, but upper part free.

Annual. Culms robust, erect, 1–1.5 m tall. Leaf sheaths smooth and glabrous; leaf blades linear, soft, 15–40 × 1–2.4 cm, glabrous, margins thickened and wavy. Inflorescence erect, lanceolate, 10–20 cm, axis robust, scabrous along edges and with tubercle-based hairs; racemes 1–3 cm, curved, simple, closely spaced and overlapping. Spikelets greenish, tardily deciduous, plump, ovate-elliptic to rotund, 2.5–3.5 mm, pubescent to hispid, awnless; lower glume 1/3–2/5 as long as spikelet; upper glume slightly shorter than spikelet; lower lemma herbaceous, sterile; upper lemma 2–3 mm. Caryopsis long persistent, eventually falling. Fl. and fr. Aug–Sep. 2n = 36, 54.

Robust annual; culms 30-150 cm high, erect. leaf-blades often broad, 5-30 cm long, 3-20 mm wide; ligule absent; sheaths glabrous. Inflorescence lanceolate, 6-20 cm long, the racemes several-rowed with crowded spikelets, 1-3 cm long, simple, closely spaced and overlapping. Spikelets broadly elliptic to rotund, 2.5-3.5 mm long, plump and sometimes gaping, ± tardily deciduous, mostly yellowish or pallid, pubescent to hispid; lower lemma acute; upper lemma 2-3 mm long.

Widely cultivated in the warmer parts of Asia and Africa.

Distribution: Pakistan (Sind, Baluchistan & Punjab); tropical East Africa south-wards to Rhodesia; India; Australia.

Fl. & Fr. Per.: Mainly September-October, but also sporadically earlier in the year.

A crop plant. Anhui, Guangxi, Guizhou, Heilongjiang, Henan, Nei Mongol, Ningxia, Sichuan, Taiwan, Yunnan [cultivated in Africa and tropical Asia].

Panicum frumentaceum Roxb., Fl. Ind. 1: 307. 1820.

Panicum frumentaceum Roxburgh, Fl. Ind. 1: 307. 1820, not Salisbury (1796); Echinochloa colona (Linnaeus) Link var. frumentacea Ridley; E. crusgalli (Linnaeus) P. Beauvois var. edulis Hitchcock, nom. illeg. superfl.; E. crusgalli var. frumen-tacea (Link) W. P. Wight; Oplismenus frumentaceus (Link) Kunth.