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Oryza punctata Kotschy ex Steudel
Family: Poaceae, Tribe: Oryzeae
Common names: red rice
Fertile floret with two glume-like sterile florets; disarticulation above the glumes (below the glume-like sterile lemmas).
Disseminule (floret with 2 sterile lemmas) elliptic to oblong, ca. 4.5-6.2 mm long, 1.9-2.6 mm wide. Callus smooth, nearly transverse. Sterile lemmas similar, glume-like, linear, glabrous, 1-1.5 mm long. Rachilla internode not pronounced below fertile lemma. Fertile lemma and palea strongly laterally compressed, keeled, cartilaginous, surface scaberulous and tuberculate in a grid pattern; lemma 5-nerved, its margins inrolled, interlocking palea margins, lemma with apical awn 10-75 mm long, slender, straight, antrorsely barbed. Caryopsis lanceolate or oblong, 5-7 mm long, laterally compressed, reddish, hilum linear, as long as caryopsis.
The wild red rices (O. longistaminata, O. punctata and O. rufipogon) can be distinguished from O. sativa L. (cultivated rice) by their red caryopses, although it may be difficult to differentiate the wild red caryopses from commercial rice cultivars with red grains.
O. punctata can be distinguished from O. rufipogon and O. longistaminata by its shorter spikelets, rachilla not pronounced between the sterile lemmas (below the floret), awns relatively slender and flexuous, and spikelets transversely (not obliquely) attached to pedicel.
Oryza longistaminata A. Cheval. & Roehr.
Oryza rufipogon Griff.
Native to tropical Africa, South Africa and Madagascar. Introduced into Thailand.
Flooded watercourses, stream banks, pond margins, rice fields.
Oryza punctata is a tufted annual grass, to 120 cm tall. See comments about the weediness of the wild red rices in the O. rufipogon fact sheet.