稗 bai

Annual. Culms coarse, erect or geniculately ascending, 20–150 cm tall. Leaf blades linear, 5–40 × 0.2–1.2 cm, usually glabrous, smooth except for scabrous margins, apex acute. Inflorescence erect, lanceolate to ovate or pyramidal, 6–22 cm; racemes 2–10 cm, usually ascending, simple or the longest with inconspicuous branchlets near the base, rachis usually with tubercle-based setae, spikelets loosely to densely crowded. Spikelets green or purplish, ovate, 2.5–4 mm, spinulose along veins; lower glume ca. 1/3 as long as spikelet, acute; lower lemma sterile, herbaceous, acuminate or extended into an awn to 3 cm; upper lemma pale brownish at maturity, elliptic, 2–3 mm. Fl. and fr. summer and autumn. 2n = 36, 48, 54, 72.

Damp weedy places, streamsides, rice fields. Throughout China [warm-temperate and subtropical regions of the world].

Echinochloa crusgalli is a widespread, polymorphic weed with many intergrading variants. The following varieties may be recognized in China: