Hairy Crabgrass

The scabrous veins of the lower lemma, although a small character requiring a good lens, are the best means of distinguishing this species from Digitaria ciliaris.

This species is a good forage grass.

Digitaria cruciata (Nees ex Steud) A. Camus is similar to, and often confused with Digitaria sanguinalis. The species is characterised by plump apiculate spikelets in which the nerves of the lower lemma are smooth, lacking the minute spines which are a feature of Digitaria sanguinalis. Neither character alone is sufficient to distinguish the two species since Digitaria sanguinalis may have equally plump spikelets or very few spines which are easy to overlook. Digitaria cruciata is confined mainly to the eastern Himalayas but extending as far west as Simla, and may only be a subspecies of Digitaria sanguinalis. No specimens corresponding to the type of Digitaria cruciata (Royle 28, LIV) have been found in Pakistan or Kashmir.

Digitaria sanguinalis is a common weed in warm temperate and subtropical parts of the Old World and has found its way into most other countries. Like Digitaria ciliaris it is polymorphic and no attempt has been made to present an infraspecific break-down; this is dealt with in some detail by Henrard.

Annuals; culms prostrate, basal nodes branching and rooting, to 3 mm in diam., to 100 cm high. Blades linear-lanceolate, 4-15 cm long, 3-9 mm wide, margins thick; ligule membranaceous, obtuse, 1- 3 mm long; sheath usually shorter than internodes, more or less tubercle hairy. Racemes 5-15 cm long, 3-10, digitately arranged; rachis ca. 1 mm wide, margins winged, green and serrulate, midrib white and ca. 1/3 as wide as rachis. Spikelets ca. 3 mm long, lanceolate, usually paired, one pedicellate and other sessile or shortly pediceled; pedicel compressed and margins serrate; lower glume minute, triangular, ca. 0.2 mm long, membranaceous; upper glume ca. 1/2-3/4 as long as spikelet, 3-veined, margins ciliated; lower lemma and upper lemma similar, nearly as long as the spikelet, 5-7-veined, median 3 veins far apart, glabrous, lateral one close and obscure, more or less ciliated along interveins and margins; upper florate cartilaginous, nearly as long as spikelet.

Annual. Culms erect or decumbent at base, 10–80 cm tall, glabrous or nodes bearded. Leaf sheaths glabrous or sparsely papillose-pilose; leaf blades linear-lanceolate, 5–20 × 0.4–1.2 cm, glabrous or pilose, margins thickened, scabrous; ligule 1–3 mm. Inflorescence digitate or subdigitate, axis 1–2 cm; racemes 4–12, stiff, 5–18 cm; spikelets paired, overlapping by about 2/3 their length; rachis winged, midrib triquetrous, margins scabrous. Spikelets elliptic-lanceolate, 3–3.5 mm, acute; lower glume small, ca. 0.2 mm, triangular; upper glume lanceolate, 1/3–1/2 spikelet length, 3-veined, pubescent, subacute; lower lemma as long as spikelet, 7-veined, veins evenly spaced or a broader interspace flanking the midvein, midvein smooth, lateral veins setiform-scabrous especially toward the apex, appressed-pubescent on lateral intervein spaces and margins, rarely also setose; upper lemma greenish gray or light brown, lanceolate, as long as spikelet, apex acuminate. Anthers ca. 1 mm. Fl. and fr. Jun–Sep. 2n = 28, 36.

Annual; culms 20.60 cm high or sometimes more, decumbent at the base, geniculately ascending. Leaf-blades broadly linear to narrowly lanceolate, 3-30 cm long, 3-17 mm wide. Inflorescence digitate or subdigitate (rarely with an axis up to 15 cm long in robust specimens), composed of 2-16 racemes; racemes stiff, 3-20 cm long, the spikelets binate and overlapping by about two-thirds their length on a winged rhachis with triquetrous midrib; pedicels triquetrous, scabrid, obtuse or slightly expanded at the tip. Spikelets narrowly elliptic to ovate elliptic, 2.3-3.5 mm long, sharply acute; lower glume an ovate scale 0.2 mm long; upper glume a third to half as long as the spikelet, 3-nerved; lower lemma as long as the spikelet, 7-nerved, the nerves evenly spaced (or occasionally with a wide interspace flanking the midrib), scaberulous on the nerves with minute siliceous spines, obscurely and appressedly pubescent, rarely with brownish glassy bristles very rarely with a ciliate frill; fruit lanceolate, grey or light brown.

The temperate and warm regions of the world. Taiwan, naturalized around villages and in waste places.

Distribution: Pakistan (Baluchistan, Punjab, N.W.F.P., Gilgit & Kashmir); warn temperate regions throughout the World, penetrating into the tropics.

Fl. & Fr. Per.: July-September.

Fields, roadsides, weedy places. Anhui, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Ningxia, Shaanxi, Shandong, Shanxi, Sichuan, Taiwan, Xinjiang, Xizang [warm-temperate and upland subtropical regions throughout the world].

Panicum sanguinalis L., Sp. Pl. 57. 1753.

Panicum sanguinale Linnaeus, Sp. Pl. 1: 57. 1753; Paspa-lum sanguinale (Linnaeus) Lamarck.