Plants annual, forming tufts or small clumps. Flowering
stems 50–160 cm long, erect, usually unbranched, glabrous. Leaf sheaths glabrous
or sparsely hairy, open for most of their length, the ligule membranous, 2‑lobed.
Leaf blades 20–50 cm long, 5–18 mm wide, flat at maturity, sometimes somewhat
thickened and spongy at the base, the base often with a pair of short auricles,
glabrous but often somewhat roughened along the midrib and margins.
Inflorescences open panicles with loosely ascending to spreading or slightly
drooping racemose branches. Spikelets numerous, short‑stalked, strongly
flattened, with 2 sterile lemmas below the 1 perfect floret, these appearing
glumelike. True glumes reduced to a minute, cuplike structure at the spikelet
base. Sterile, glumelike lemmas 1.5–3.0 mm long, similar in size and
appearance, narrowly lanceolate, sharply pointed at the tip, faintly 1‑nerved,
glabrous. Fertile lemma 7–10 mm long, strongly keeled, oblong‑obovate,
pointed at the tip, awnless or the awn 1–5 mm long, the surface glabrous,
pebbled, or hairy, with a fine network of wrinkles, 5‑nerved. Palea
similar in size and appearance to the lemma, but somewhat narrower and with
only 2 marginal nerves. Stamens 6. Fruits 6.5–7.0 mm long, elliptic in outline,
white or nearly so, enclosed by the persistent lemma and palea, which harden at
maturity. 2n=24. June–September.
Introduced, escaped sporadically from cultivation in the
Mississippi Lowlands Division and in Lincoln and Marion Counties (widely
cultivated in warmer parts of the world, escaping sporadically in the southern U.S.). Roadside depressions and ditches.
among the world’s most important crop plants, with uses ranging from the well‑known
edible grain to the use of fibers for paper manufacture. In parts of Asia it is used for distillation of alcohol. The cultivated taxon was developed from plants
probably native to Asia. Numerous cultivars of three subspecies often are
recognized in the literature on the species’ domestication (Tucker, 1988).
Cultivation in Missouri is mostly restricted to portions of the Mississippi
Lowlands and the Mississippi River floodplain farther north. Hulls (persistent
lemmas and paleas) from the Missouri rice crop have been used as a component of
potting mix for commercial production of ornamental shrubs and trees. The rice
fields are an important habitat for a variety of bird species when flooded in
the early spring. They also provide habitats for various amphibians and other
small aquatic fauna, as well as an array of weedy aquatic plant species.
Escaped plants of rice in Missouri probably do not persist for very long in the