Oryza latifolia Desvaux var. silvatica Camus; O. minuta Presl var. silvatica (Camus) Veldkamp.

Perennial. Culms erect or creeping and rooting at lower nodes, 1.5–3 m tall, 7–10 mm in diam. Leaf sheaths more than 3 times internode length, auricles inconspicuous; leaf blades thick, 30–50 × 2–3 cm, abaxial surface and margins scabrous, adaxial surface scattered villous, midrib stout, lateral veins inconspicuous, base narrowed, puberulous, apex acuminate; ligule 1–4 mm. Panicle loosely contracted, 30–50 cm, base often included in terminal sheath; branches 3–5 at lowest node, axils bearded, longest 10–25 cm, naked in lower half, apices of lowermost branches drooping. Spikelets broadly ovate-oblong, 4–5 mm, length 1.5–2 times width, yellowish green or tinged brownish black, deciduous; sterile lemmas linear-lanceolate, 1.5–2 mm, apex acuminate; fertile lemma papillose, keel and marginal veins with hard glassy hairs; awn 5–10(–25) mm, slender, scabrid. Anthers 1.5–2.5 mm. Caryopsis reddish brown, ca. 3 × 2 mm. 2n = 24.

The name Oryza latifolia Desvaux has sometimes been misapplied to this species in Asian literature.

Oryza officinalis is normally diploid, with the genome CC. It is closely related to the tetraploid O. minuta Presl from the Philippines (genome BBCC), and is sometimes placed as O. minuta var. silvatica. Oryza minuta differs only slightly morphologically, the lowermost panicle branches having a shorter naked portion and ascending at the tip. It also has proportionately narrower spikelets with length 2–2.7 × width.

Low hills, alluvial plains, ditch banks; below 1000 m. Guangdong, Guangxi, Hainan, Yunnan [Bhutan, Cambodia, India, Indonesia, Malaysia, Myanmar, Nepal, New Guinea, Philippines, Sri Lanka, Thailand, Vietnam].