Setaria pumila

The name Setaria glauca (Linnaeus) P. Beauvois has been misapplied to this species.

Setaria pumila and S. parviflora are different facets of the same polymorphic complex, and are sometimes regarded as a single, variable species. No character taken on its own is reliable for separating the two species, but the combination of all characters listed in the key will enable most specimens to be assigned to one or the other.

The name Setaria lutescens var. dura refers to a form with the lower lemma hardened and rugose like the upper lemma. This is a rare variant, known from Fujian and Yunnan and also from Korea. Hardening of the lower floret is known to occur occasionally in other genera of Paniceae.

This species is cultivated for forage.

Panicum pumila is a polymorphic weed segregating into regional populations. These overlap to such an extent that the recognition of more than one species cannot be upheld, though there may be a case for distinguishing between tropical and Mediterranean populations at infra-specific level (see Clayton in Kew Bull. 33:501. 1979). Much argument has been devoted to the nomenclature of this species (summarised by Terrell in Taxon 25:297-304. 1976), but it now seems that the commonly used name Panicum glauca should be referred to Pennisetum.

Panicum pumila is closely related to the caespitose perennial Panicum sphacelata (K. Schum.) Moss, and specimens lacking their basal parts are often indistinguishable. The latter is a native of tropical and South Africa introduced to India (but not, thus far, to Pakistan) as a fodder grass. Panicum pumila is even more difficult to separate from another introduction, Panicum gracilis Kunth (Panicum geniculata auct. non (Willd.) P. Beauv.), which occurs in America and tropical Asia. This is a short-lived perennial, commonly with short knotty rhizomes bearing dormant buds, though the perennial habit is usually not very obvious.

Annual. Culms erect or geniculate, 20–90 cm tall, smooth or scabrous just below inflorescence, nodes glabrous. Leaf sheaths keeled, glabrous; leaf blades linear, 5–40 × 0.2–1 cm, abaxial surface smooth, adaxial surface scabrous or pilose at base; ligule ca. 1 mm. Panicle densely cylindrical, 3–17 × 0.4–0.8 cm; branches reduced to a single mature spikelet subtended by 5–10 or more bristles (sometimes an aborted spikelet also present); axis pubescent; bristles gold, brownish gold or sometimes purple, 2–3 times spikelet length. Spikelets broadly ovate, (2.2–)2.5–3.5 mm; glumes ovate; lower glume 1/3–1/2 as long as spikelet; upper glume 1/2–2/3 as long as spikelet; lower floret usually staminate; lower palea hyaline, ovate, matching the upper floret in size and shape, keels narrowly winged; upper lemma broadly ovate, coarsely rugose. Fl. and fr. Jun–Oct. 2n = 18, 36.

Loosely tufted annual; culms 5-130 cm high, ascending. Leaf-blades linear, 3-30 cm long, 2-10 mm wide. Panicle spiciform, cylindrical, 1-10(20) cm long, the rhachis tomentellus; bristles 3-12 mm long, slender, commonly fulvous. Spikelets ovate, 1.5-3.5 mm long; both glumes one-third to two-thirds the length of the spikelet; lower floret male or sterile, its palea almost as long as the lemma; upper lemma rugose to corrugate, rarely almost smooth.

Distribution: Pakistan (Sind, Baluchistan, Punjab, N.W.F.P., Gilgit & Kashmir); tropical and warm temperate regions of the Old World; introduced to North America.

Fl & Fr. Per.: June-October.

Waste places, mountain slopes, roadsides, forest margins. Anhui, Beijing, Fujian, Guangdong, Guizhou, Hainan, Heilongjiang, Henan, Hubei, Hunan, Jiangxi, Ningxia, Shaanxi, Shandong, Shanghai, Sichuan, Taiwan, Xinjiang, Xizang, Yunnan, Zhejiang [originally from temperate and subtropical Asia and Europe, but now widespread].

Panicum pumilum Poiret in Lamarck, Encycl., Suppl. 4: 273. 1816; Setaria glauca (Linnaeus) P. Beauvois var. dura (I. C. Chung) I. C. Chung; S. lutescens (Weigel ex Stuntz) F. T. Hubbard var. dura I. C. Chung.