Oryza longistaminata

Name and classification

Oryza longistaminata A. Cheval. & Roehr.
Family Poaceae, Tribe Oryzeae

Common names

red rice

Disseminule

fertile floret with two glume-like sterile lemmas; disarticulation above the glumes (below the sterile lemmas)

Description

Disseminule (floret with 2 sterile lemmas) oblong, ca. 7–9 mm long, 2–3 mm wide; callus smooth; disarticulation scar lateral. Sterile lemmas similar, glume-like, linear, glabrous, 2–4.5 mm long; apex sometimes trilobed with the central lobe longer than the lateral lobes. Rachilla internode pronounced below fertile lemma; referred to as a "stipelike callus". Fertile lemma and palea strongly laterally compressed, keeled, cartilaginous, surface scaberulous and tuberculate in a grid pattern. Lemma 7–9 mm long, 5-nerved; its margins inrolled, interlocking palea margins; with apical awn 26–150 mm long, straight, antrorsely barbed. Caryopsis lanceolate or oblong, 5–8.5 mm long, laterally compressed, reddish, hilum linear, as long as caryopsis.

Identification considerations

The wild red rices (Oryza 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.

The disseminules of O. rufipogon and O. longistaminata are difficult to differentiate morphologically. However, the two species are distinct geographically; O. rufipogon is not found in Africa, while O. longistaminata is found mostly in Africa.

Similar species

Oryza punctata Kotschy ex Steudel

Oryza rufipogon Griff.

Distribution

tropical Africa, South Africa, and Madagascar

native to tropical Africa

Habitat

deep water, standing or running water, salt marshes, dry, sandy fields

General information

Oryza longistaminata is a rhizomatous perennial grass, to 120 cm tall. This species is believed to be the wild progenitor of O. glabberrima Steud., the African cultivated rice. The evolution of O. glabberrima parallels that of O. sativa L. See comments about the weediness of the wild red rices in the Oryza rufipogon fact sheet.

disseminules in side view

disseminules in side view

disseminules and caryopses; photo by Mark Thurmond

disseminules and caryopses; photo by Mark Thurmond

A, fertile floret with 2 attached sterile lemmas; B, caryopsis in side view showing embryo; drawing by Lynda E. Chandler

A, fertile floret with 2 attached sterile lemmas; B, caryopsis in side view showing embryo; drawing by Lynda E. Chandler