Jonsonindurra

This grass was introduced at some early period, however, it is now naturalized in waste places. It has been widely cultivated as fodder.

This species is thought to have originated in the Mediterranean region, but is now widely distributed as a serious weed in warm-temperate regions of the world. The forage known as Johnson Grass is a selection of Sorghum halepense. It introgresses with grain sorghum (S. bicolor) where both species grow together.

Snowden (in J. Linn. Soc., Bot. 55:199. 1955) considers that Sorghum halepense reaches the eastern limit of its range in Kashmir and that it is not native in India. It is widely grown in temperate regions, especially North America, as Johnson Grass, and has been introduced into most warm countries.

Because of its tenacious rhizomatous habit Sorghum halepense has earned a bad reputation as a weed of cultivated fields. Worse than this, under certain circumstances its tissues contain hydrocyanic acid and are a positive danger to stock.

Endrezzi (in Bot Gaz. 119: 1. 1957) considers that Sorghum halepense arose as a segmental allotetraploid from a cross involving Sorghum propinquum (2n=20) and a member of Subsect. Arundinacea (2n=20). Sorghum propinquum extends from China to the Malay Peninsula, but does not occur in India, and is the only diploid Halepensia.

Culm erect, solid, 2.5-3 mm in diameter. Blade linear, up to 30 cm long by 8 mm wide, basal part densely covered with silky hairs; ligule about 1.8 mm long, ciliate. Panicle large. Spikelets paired, dimorphic; the upper pedicelled, linear-oblong, 1/2 the width of the sessile spikelet, purplish-black; the lower sessile, broadly lanceolate, about 4 mm long. Glumes coriaceous, as long as the spikelet; the lower broadly lanceolate, 2-keeled, ciliate on the back, 5-7-nerved, tessellate-nerved; the upper lanceolate, boat-shaped, 3-nerved, also tessellate nerved, margins inrolled, membranous, fimbriate and hirsute on the upper back, 1-keeled. Lower floret reduced to a lemma, membranous, as long as the glume, 3-nerved, margins fimbriate. Upper floret membranous; lemma deltoid-lanceolate, about 2 mm long, 1-3-nerved, slightly thickened toward the end of middle nerve; palea linear or irregular, fimbriate on the upper part, about 1.5 mm long; stamens 3; anthers about 1.8 mm long.

Perennial with vigorous spreading rhizomes. Culms 0.5–1.5 m tall, 4–6 mm in diam.; nodes puberulous. Leaf sheaths glabrous; leaf blades linear or linear-lanceolate, 25–80 × 1–4 cm, glabrous; ligule 0.5–1 mm, glabrous. Panicle lanceolate to pyramidal in outline, 20–40 cm, soft white hairs in basal axil; primary branches solitary or whorled, spreading, lower part bare, upper part branched, the secondary branches tipped by racemes; racemes fragile, composed of 2–5 spikelet pairs. Sessile spikelet elliptic, 4–5 mm; callus obtuse, bearded; lower glume subleathery, often pale yellow or yellowish brown at maturity, shortly pubescent or glabrescent, 5–7-veined, veins distinct in upper part, apex 3-denticulate; upper lemma acute and mucronate or 2-lobed and awned; awn 1–1.6 cm. Pedicelled spikelet staminate, narrowly lanceolate, 4.5–7 mm, often violet-purple. Fl. and fr. summer–autumn. 2n = 40.

Rhizomatous perennial; culms simple or branched, 0.5-3 m high or more, slender to rather stout. Leaf-blades 20-90 cm long, 0.5-4 cm wide. Panicle loose when in flower, sometimes somewhat contracted after flowering, lanceolate to pyramidal, mostly 10-55 cm long, 3-25 cm wide; primary branches compound, bare at the base, ultimately bearing racemes of 1-5 spikelet pairs. Sessile spikelet elliptic to subelliptic, 45-5(-5.5) mm long, at first ± hairy and cream to buff-yellow or twany, at the length often tawny, mahogany red, purplish to blackish brown or black and sometimes almost glabrous; lower glume keeled above, the wings of the keels widening upwards to end in minute teeth, forming with the short apex a distinctly 3-toothed tip; upper lemma acute and minutely mucronate or 2-lobed with an awn 10-16 mm long. Pedicelled spikelet at length deciduous, often purplish, male, 4.5-6.5 mm long. 2n=40.

India & most warm countries, widely cultivated.

Distribution: Pakistan (Sind, Baluchistan, Punjab, N.W.F.P., Gilgit & Kashmir); Mediterranean region eastwards to Kashmir and southwards to Madras.

? m

Fl. & Fr. Per.: May-October.

Introduced. Streams, valleys, waste ground, a weed in fields. Anhui, Fujian, Guangdong, Hainan, Sichuan, Taiwan, Yunnan [India, Kazakhstan, Kyrgystan, Nepal, Pakistan, Sri Lanka, Tajikistan, Turkmenistan, Uzbekistan; SW Asia, S Europe].

Holcus halepensis L. var. genuinus Honda, Bot. Mag. Tokyo 40: 99. 1926, Monogr. 333. 1930.

Holcus halepensis Linnaeus, Sp. Pl. 2: 1047. 1753; Andro-pogon halepensis (Linnaeus) Brotero; A. sorghum (Linnaeus) Brotero subsp. halepensis (Linnaeus) Hackel.