Rice Field Grass

Echinochloa oryzoides is adapted as a weed of rice (Oryza), which it resembles in habit. A variant from ricefields in Italy has a dense band of hairs on the outer side of the leaf sheath and blade junction, particularly on the lower leaves. This is the basis of the name E. phyl-lopogon.

Echinochloa oryzoides is a rice mimic and can be a serious weed in rice fields. In parts of southern Russia the infection has been so bad that the cultivation of rice has had to be abandoned whereupon the weed has taken over the rice fields.

Annual. Culms erect, forming a narrow tuft up to 1 m tall. Leaf sheaths and blades glabrous or rarely lower leaves with a dense tuft of hairs on abaxial side at junction of sheath and blade; leaf blades stiffly erect, linear, flat, 10–30 × 1–1.5 cm, margins thickened and scabrous. Inflorescence 8–15 × 1.5–3 cm; racemes simple. Spikelets light green, ovate, 3.8–6 mm; glumes hispid along veins, lower glume 1/2–2/3 as long as spikelet, acuminate; upper glume acuminate; lower lemma acuminate or with an awn up to 2 cm; upper lemma 3.5–5 mm. Fl. and fr. Jul–Oct. 2n = 54.

Annual; culms 25-150 cm high, erect. Leaf-blades 7-35 cm long, 5-12 mm wide; ligule absent; sheaths smooth and glabrous. Inflorescence linear to narrowly ovate, 6-25 cm long, the racemes irregularly 2-rowed, the longest 2-5 cm long, usually simple. Spikelets ovate-elliptic, 3.8-6.5 mm long, hispid; lower lemma acuminate or with an awn up to 2.5 cm long; upper lemma 3.5-5 mm long, including the short herbaceous tip.

Distribution: Pakistan (N.W.F.P. & Kashmir); Southeast Asia; introduced to much of Russia and parts of southern Europe.

Fl. & Fr. Per.: August.

A weed of rice fields. Anhui, Guangdong, Guizhou, Hainan, Hebei, Henan, Hunan, Jiangsu, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan [India, Indonesia, Japan, Kazakhstan, Korea, Kyrgyzstan, Pakistan, Russia, Turkmenistan, Uzbekistan; Europe, America].

Panicum oryzoides Arduino, Animadv. Bot. Spec. Alt. 16, t. 5. 1764; Echinochloa coarctata Kossenko; E. crusgalli (Linnaeus) P. Beauvois subsp. oryzicola (Vasinger) T. Koyama; E. crusgalli var. oryzicola (Vasinger) Ohwi; E. macrocarpa Vasinger; E. oryzicola (Vasinger) Vasinger; E. oryzoides subsp. phyllopogon (Stapf) Tzvelev; E. persistentia Z. S. Diao; E. phyllopogon (Stapf) Stapf ex Kossenko; E. phyllopogon subsp. oryzicola (Vasinger) Kossenko; Panicum oryzicola Vasinger; P. phyllopogon Stapf.