巨大狗尾草 ju da gou wei cao

Panicum pycnocomum Steudel, Syn. Pl. Glumac. 1: 462. 1854; P. viride var. giganteum Franchet & Savatier; P. viride var. majus Gaudin; Setaria gigantea (Franchet & Savatier) Makino; S. pycnocoma (Steudel) Henrard ex Nakai; S. viridis var. major (Gaudin) Petermann (1838), not Gray (1821).

Culms little branched at base, 60–150 cm tall. Leaf blades 15–40 × 1–2.5 cm, glabrous on both surfaces. Panicle sometimes lobed, 7–24 × 1.5–2.5 cm; bristles green, brownish or purplish, 7–12 mm. Spikelets 2.5–3 mm. Fl. and fr. Jun–Oct.

Roadsides, forest margins, a crop weed, especially in Setaria itali-ca fields; below 2700 m. Gansu, Guizhou, Hebei, Heilongjiang, Hong Kong, Hubei, Hunan, Jilin, Nei Mongol, Shaanxi, Shandong, Sichuan, Xinjiang [Japan, Russia; C and SW Asia, C and S Europe, North America].

This robust form of Setaria viridis may be of hybrid origin, resulting from crossing with S. italica. Unlike Setaria italica, the spikelets are shed whole.