Echinochloa colona (L.) Link, awnless barnyard grass, jungle rice, shama millet. Annual, fibrous–rooted and forming adventitious roots at lower nodes, several—many–stemmed at base, cespitose, decumbent or spreading to ascending, in range to 50 cm tall; shoots with basal leaves, cauline leaves, and conspicuous prophylls, appearing glabrous.
Stems (culms) compressed–cylindric, to 5 mm diameter, tough, often jointed (geniculate) at lower nodes near soil, internodes to 140 mm long and glabrous, nodes with appressed short hairs; internodes spongy–solid and sometime torn but not hollow, core white.
Leaves alternate distichous, simple with sheath; prophyll strongly 2–keeled with deep trough between keels, 30—160 mm long, often > internode, open, long–tapered to tip, minutely short–toothed along keels; sheath open, < 50—150 mm long, rounded on back, without lobes (auricles) at top, short–hairy from base to 5 mm; ligule absent; collar white and purplish, with several stiff long hairs having nipplelike base, often with appressed short hairs on outer (lower) surface; blade linear, in range 50—280 × 6—11 mm, the widest near midblade, somewhat folded upward from midrib to midblade and flat above midblade, sparsely minutely toothed on margins, long–tapered at tip, parallel–veined with broad midrib defined and somewhat raised on lower surface, surfaces glabrous or with inconspicuous, sparse, short–pilose hairs, lower surface with minute teeth along midrib.
Inflorescence spikelets, in terminal panicle, flag leaf blade = inflorescence (including exposed peduncle) and partially concealed in flower, panicle 100—160 mm long, of 7—15 ascending, spikelike primary branches, branches ascending to widely spreading, < 5—40 × 2—4 mm and lacking branchlets, spikelets in subsessile clusters in 4 or 6 rows restricted to outer faces of primary branches, spikelet having 2 florets with a sterile lower floret and fertile upper floret, bracteate, lacking awns; main axis ridged, lower internodes often glabrous but with short and a tuft of long hairs at junction with each primary branch, the hairs 2—4.5 mm long, nipplelike at base, and colorless; primary branches typically 3–ridged or even winglike, in range mostly 10—35 mm long, weakly wavy, minutely scabrous along edges and short–hairy; spikelet stalk 0.2—0.5 mm long, with a ring of exlarged cells at place where spikelike abscises.
Spikelet ± obovoid, in range 2—2.5 × 1.2—1.3 mm, breaking below glumes; glumes 2, unequal and dimorphic, greenish or red–purple; lower glume sheathing spikelet base, ovate, ± 1 mm long, acute with short point at tip, 3–veined and colorless with green lateral veins directed upward to margins or arching toward midvein below tip but at least 1 not reaching midvein, short–hairy on back, short–ciliate on margin; upper glume broadly boatlike and obovate, 2—2.4 mm long; lower glume < upper glume, inrolled on margins, short–pointed at tip, typically 7–veined but 5–veined base–to–tip and with extra veins from a forking of the lateral veins closest to midvein, puberulent between veins, short–bristly along veins; lemma of lower floret lacking awns, elliptic, ca. 2 mm long, acute at tip, greenish with raised veins on back, 7–veined but 5–veined base–to–tip and with extra veins from a forking of lateral veins closest to midvein, short–ciliate on margins above midpoint, puberulent between veins, short–bristly along veins, inrolled on margins, lacking awn; palea oblong rounded at tip with margins folded inward to about midpoint, 2 × 0.8 mm, membranous, 2–veined, veins colorless; lemma of upper floret boatlike and strongly cupped, ca. 1.6—1.9 mm long, faintly 5–veined, acute at tip, mostly glabrous but minutely hairy at papery tip, with margins clasping palea, at anthesis pale green and ± leathery becoming whitish and hard in fruit; palea ovate, < lemma, flat with inrolled margins, at anthesis pale green and ± leathery becoming whitish and hard in fruit, with 2 lateral veins where margins inrolled (not keeled), glabrous.
Flower (upper floret) bisexual; perianth (lodicules) 2, at anthesis fleshy and broadly fan–shaped, 0.3—0.4 mm long, length < width, translucent–colorless; stamens 3, free; filaments threadlike, ca. 1.5 mm long, white; anthers exserted, basifixed, dithecal, 0.6—0.8 mm long, cream–colored to pale yellow, longitudinally dehiscent; pollen whitish; pistil 1; ovary superior, ellipsoid, 0.5 × 0.3 mm, glossy translucent–colorless, glabrous, 1–chambered with 1 ovule; styles 2, stigmatic portion exserted above midpoint of lemma, lower portion in fresh condition the pair omega–shaped, each 1.2—1.3 mm long and colorless, upper exserted portion, feathery (plumose) and stigmatic, ca. 0.6 mm long, red–purple.
Fruit achene (caryopsis), firmly enclosed by hard, glossy lemma and palea, the unit hemi–ellipsoid, 1.6—1.8 mm long, at maturity pale green with fine veins, concealing white, ellipsoid achene ca. 1.3 mm long.
A. C. Gibson