Oryza sativa L.

Global description

Oryza sativa in its weedy rice aspect comes in various forms, all from the cultivated rice which it looks like in numerous ways. At the beginning of the vegetation phase, it germinates with the crop, hence the difficulty of controlling it. It is distinguished by its size which is generally superior. The spikelets are more or less awned. Its faster maturation and the early deciduous spikelets allows it to escape the harvest. These weedy rice occurs in all the rice fields all around the world.

General habit

Annual grass up to 1.5 m tall. The weedy rice also called "crodo" or "red rice" is named because of the sometimes reddish color of its grain. In this way, these kinds of weedy rice comes from cultivated rice are known to develop in rice paddies such as wild rice and thus compete with the crop. They are faster-growing than the cultivated form, whose grain matures earlier and and fall down as soon as mature, thus avoiding harvesting and contaminating the plot. Weedy rice has the same appearance as normal rice, but is a bit higher and some times awned.

Underground system

The roots are fibrous, fasciculate. Adventitious roots are formed from the lower nodes.

Culm

The culm is erect, geniculate, elliptic in section at the base and hollow. It measures up to 1.5 m in height.

Leaf

The sheath is shorter than the blade, smooth, of a light green color. The translucent membranous ligule is triangular elongated, 15 to 45 mm long, acute at the apex and often bifid. It is framed at the base by 2 elongated ciliated auricles. The limb is usually erect, more or less scabrous on both sides, scabrous margin. The blade is narrowed at the base and acute at the top.

Inflorescence

The inflorescence is a loose panicle relatively open, from 15 to 40 cm, with branches arranged around the axis, rather bent at maturity.

Spikelet

The spikelets are oblong, 8 to 15 mm long, aristate or not, if so 30 to 40 mm long. Glumes reduced to a membranous bead.
The sterile inferior flower greatly reduced to a lemma. The fertile superior flower has a tough lemma and palea navicular, keeled, laterally compressed and hispid. The lemma may or may not be awned.

Grain

Grain up to 8 mm long, ovate-lanceolate to elliptic-lanceolate, elongate and tapered at the ends, sometimes red or brown.

https://www.gbif.org/species/2703459