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.

Annuals, Aquatic, leaves emergent, Terrestrial, not aquatic, Stems nodes swollen or brittle, Stems erect or ascending, Stems caespitose, tufted, or clustered, Stems terete, round in cross section, or polygonal, Stem internodes solid or spongy, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems with inflorescence 1-2 m tall, Stems, culms, or scapes exceeding basal leaves, Leaves mostly cauline, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades 1-2 cm wide, Leaf blades mostly flat, Leaf blade with prominently raised or widened midvein, Leaf blades mostly glabrous, Inflorescence terminal, Inflorescence an open panicle, openly paniculate, branches spreading, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence a panicle with narrowly racemose or spicate branches, Inflorescence branches more than 10 to numerous, Inflorescence branches 1-sided, Rachis angular, Flowers bisexual, Spikelets pedicellate, Spikelets sessile or subsessile , Spikelets dorsally compressed or terete, Spikelet less than 3 mm wide, Spikelets with 1 fertile floret, Spikelets with 2 florets, Spikelet with 1 fertile floret and 1-2 sterile florets, Spikelets paired at rachis nodes, Spikelets all alike and fertille, Spikelets in paired units, 1 sessile, 1 pedicellate, Spikelets bisexual, Spikelets disarticulating below the glumes, Spikelets secund, in rows on one side of rachis, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes distinctly unequal, Glumes shorter than adjacent lemma, Glumes equal to or longer than adjacent lemma, Glumes awned, awn 1-5 mm or longer, Glumes keeled or winged, Glume surface hairy, villous or pilose, Glumes 4-7 nerved, Lemma coriaceous, firmer or thicker in texture than the glumes, Lemma becoming indurate, enclosing palea and caryopsis, Lemma 5-7 nerved, Lemma glabrous, Lemma apex dentate, 3-5 fid, Lemma awnless, Lemma margins inrolled, tightly covering palea and ca ryopsis, Lemma straight, Palea present, well developed, Palea longer than lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis.

Echinochloa oryzoides is a species of grass known by the common name early barnyard grass. Its origin is not certain but it may be Eurasia. The grass has been identified as a major weed of rice paddies and has been known to mimic rice.