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(Last Modified On 10/30/2013)
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Species
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Panicum sabulorum Lam.
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PlaceOfPublication
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Encycl. 4: 744. 1798.
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Synonym
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Dichanthelium sabulorum (Lam.) Gould & C. A. Clark, Ann. Missouri Bot. Gard. 65: 1112. 1978.
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Note
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TYPE: Uruguay. Montevideo: Monte- video, Commerson s.n. (holotype, P; isotypes, R, US, fragment BAA).
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Description
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Short-rhizomatous perennials. Culms dimorphic: young culms simple, erect and with broad, cordate, lanceolate leaves, older culms erect to decumbent, occasionally rooting and profusely branching at the lower and upper nodes, up to 1 m long, with the leaves smaller than those of the simple culms; in- ternodes hollow, cylindric, hirsute; nodes densely pilose to glabrous, dark. Sheaths 2.5-6 cm long, hirsute to glabrous, the margins ciliate, glands pres- ent or absent, more conspicuous toward the distal portion. Ligules membranous-ciliate, 0.4-1.1 mm long; collar pilose or glabrous. Leaves lanceolate, 1-9(-15) cm long, 0.2-1.4(-2) cm wide, flat, sub- cordate to cordate, amplexicaulous, acuminate, rigid to herbaceous, pubescent, with short, stiff hairs or with papillose-pilose hairs or glabrous, the lower margins long-ciliate, otherwise scabrous, the mid- nerve inconspicuous. Primary inflorescences lax, diffuse, few to multiflowered, 2-10 cm long, 2-8 cm wide; main axis hirsute or glabrous, with or without glands; first-order branches alternate, di- vergent, the axis of the branches long-hirsute to scabrous and with or without glands; spikelets paired or solitary on claviform pedicels; pedicels hirsute and with or without glands. Axillary panicles similar to the terminal one but smaller. Spikelets obovoid, biconvex, 1.9-3 mm long, 0.9-1.4 mm wide, short- ly stipitate, greenish and tinged with purple, hirsute to glabrous; glumes and lower lemma with manifest nerves. Lower glume 3-5-nerved, ?1/2- the length of the spikelet, ovate, obtuse to acute and embracing the upper glume on its base, the nerves anastomosed toward the apex. Upper glume 7-9-nerved, obtuse, not covering the apex of the upper anthecium. Low- er lemma glumiform, 7-9-nerved. Lower palea ovate, 1.6 mm long, 0.8 mm wide, hyaline, the margins short-ciliate. Lower flower male or absent. Upper anthecium broadly ellipsoid, 1.8-2.5 mm long, 0.7-1.2 mm wide, stramineous, shiny, shortly apiculate, with simple papillae in regular rows; lem- ma 5-nerved. Upper flower bisexual; lodicules 2, truncate and embracing the lower margins of the palea; stamens 3, styles 2, free, stigma purplish. Caryopsis broadly ellipsoid, 1.5 mm long, 1 mm wide; hilum punctiform; embryo less than half the length of the caryopsis.
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Key
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Key to the Varieties la. Blades amplexicaulous ........... var. cordatum lb. Blades not amplexicaulous. 2a. Spikelets (2.2-)2.4-3 mm long, pilose; blades pilose; plants growing in open, dry places ..................... var. sabulorum 2b. Spikelets 1.9-2.3(-2.6) mm long, glabrous or sparsely pilose; blades glabrous; plants growing at edge of forest in humid places ......................... var. polycladum
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