Rhynchospora radicans subsp. radicans
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Authority
Thomas, William W. 1984. The systematics of Rhynchospora section Dichromena. Mem. New York Bot. Gard. 37: 1-116.
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Family
Cyperaceae
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Scientific Name
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Description
Subspecies Description - Cespitose, mostly glabrous annual or short-lived perennial; culms arching, 860 cm long, 3-6.5 mm in diameter, triquetrous or obtusely so, green; leaves mostly cauline, 2-11 per culm, green, flat to involute, nerved, ciliate basally along margin of blade; basal leaves 1-5, sometimes reduced but commonly to 7 cm long and occasionally to 22 cm long, 1-3.5 mm wide; cauline leaves 2-6 with longest blades 4-33 cm long, 1.3-4.5 mm wide; leaf sheaths 1.5-5 cm long, green, nerved, pubescent along inner band below summit and, occasionally, elsewhere; summit of inner band concave, ciliate, brownish-hyaline along central strip; inflorescence bracts green, 2-5 exceeding inflorescence, strongly reflexed to occasionally spreading, usually becoming more reflexed with age, sometimes short-pubescent abaxially, ciliate basally along margins; basal bract longest, 1.8-7.5 cm long, 1.1-2.5 mm wide; inflorescence (Fig. 22b) a single ovoid spikelet, rarely as many as 3 spikelets, especially when plant is viviparous; spikelets consisting of 20-40 scales, 7-10 mm long, 2.5-4 mm wide; scales ferrugineous, white when young, ovate, 4 5-6 mm long, 2.3-4.3 mm wide, cymbiform, weakly carinate distally; filaments 4.4-5.7 mm long; anthers 2.5-3.3 mm long; stigma and style 3.2-5 mm long; stigma branches 1.4-4.1 mm long; achenes lenticular, bilaterally symmetrical, widely depressed obovate, 0.9-1.4 mm long, 1.1-1.6 mm wide, stramineous to castaneous; summit of achene arched; shoulders of achene at edge of style base not confluent with achene margin; style base shallowly to very shallowly triangular or very occasionally shallowly lunate, 0.3-0.6 mm high, 1.05-1.6 mm wide, brown to grey; achene surface transversely rugulose; epidermal cells of achene narrowly elliptic, ± indistinct. Flowering and Fruiting: all year. Distinguishing Features: Rhynchospora radicans is characterized by its larger central spikelet (single in ssp. radicans) and its brownish spikelet scales. It is frequently viviparous with plantlets sprouting from the bases of the spikelets. Rhynchospora radicans ssp. radicans can be distinguished from ssp. microcephala by its single, brownish spikelet subtended by reflexed bracts on a graceful, arching culm; the differences between the two subspecies are discussed further under ssp. microcephala.
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Discussion
Dichromena tenuis Steudel, Syn. Pl. Cyperacearum 135. 1855. Type: Mexico, Oaxaca, 1840, Galeotti 5860 (P?, holotype, not seen; F, GH, NY-2, US, isotypes).
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Distribution
Habitat: moist, disturbed, usually partially shaded areas such as forest edges, trails and clearings.
South America| Central America|