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10. Eleocharis R. Brown, Prodr. 1: 224. 1810; C.B.Clarke in Hook.f., Fl. Brit. Ind. 6: 625. 1893; R.R.Stewart, l.c. 93. 1972.
Annual or perennial plants. Rhizome often sturdy, horizontal, frequently producing stolons, which may end with tuber or bulbil. Leaves reduced; lowest open sheaths loosely surrounding stem base, scarious, soon disintegrating; above them two closed sheaths tightly surrounding stem base; blades 0; ligule 0. Inflorescence a single spike, glumes spirally arranged, all fertile or lowest 1-2 sterile. Flowers bisexual; perianth bristles 3 to 8, conspicuous or small, retrorsely barbed, occasionally absent; stamens 3-2; stigmas 2-3; stylopodium persistent on top of mature nut, distinguished by its softer, often spongy texture, in most cases bulbous and clearly separated from nut by constriction. Nut 0.5-2.5 mm, excl. stylopodium, trigonous or lenticular.
Eleocharis resembles Schoenoplectus in having reduced leaf blades, characteristically, there are two closed sheaths at stem base and inflorescence is a single spike. Style base is swollen as in Abildgaardia and Fimbristylis, but in these genera the stylopodium is caducous, in Eleocharis it persists. The style base in E. quinqueflora is conical and stylopodium tissue is visible only when wet. The small stylopodium of Bulbostylis may be persistent, but Abildgaardia, Fimbristylis and Bulbostylis species all have well-developed leaf blades. Trichophorum is also unispikate, but characterized by short leaf blades and by absence of stylopodium. For subgeneric division, see Kukkonen, Ann. Bot. Fennici 27: 109-117. 1990, Gonzalez-Elizondo & Peterson, Taxon 46: 433-499. 1997.
A genus with c. 150 cosmopolitan species; represented in Pakistan by c. 10 species.
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| 1 (1) |
Annuals or perennials forming small tufts. |
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(1) |
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Perennials with horizontal rhizome or stolons. |
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(2) |
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| 2 (1) |
Stem less than 0.5 mm diam.; glumes in 5 spiral rows, 1.1- 1.6 mm, with strong, green midnerve; perianth bristles 4- 7, shorter than or equalling nut; nuts 0.6-0.8 mm. |
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9 E. atropurpurea |
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Stem more than 0.5 mm diam.; glumes not in protruding spiral rows, 1.5-2.2 mm, midnerve not very strong; perianth bristles 6-8, longer than or equalling nut; nuts 0.8-1 mm. |
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(3) |
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| 3 (2) |
Basal glume fertile, not distinct from other glumes; stigmas 2; stylopodium much wider than long. |
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10 E. geniculata |
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Basal glume sterile, larger than the other; stigmas 3; stylopodium as long as wide or longer. |
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8 E. congesta |
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| 4 |
Robust perennial, up to 1.4 m, stem septate. |
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1 E. dulcis |
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Mostly less robust plants, up to 1 m, stem not septate. |
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(5) |
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| 5 (4) |
Stem sharply angular, slender, 0.5-1 mm diam.; stylopodium 1.1-1.2 mm. |
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7 E. tetraquetra |
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Stem terete or, at most, obscurely angular, 0.2-3 mm diam., stylopodium shorter, less than 1 mm. |
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(6) |
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| 6 (5) |
Plants 3-30 cm, stem 0.2-0.75 mm diam., terete or obscurely angular, style base not distinctly bulbous. |
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6 E. quinqueflora |
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Plants (5-)15-100 cm, stem 1-5 mm diam., terete, style base bulbous stylopodium. |
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(7) |
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| 7 (6) |
Base of spikes a single clasping, sterile glume. |
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5 E. uniglumis |
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Base of spikes with two more or less equal, sterile glumes. |
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(8) |
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| 8 (7) |
Plants to c. 30 cm; perianth bristles 0-4, to equalling nut; stylopodium 0.4-0.5 x 0.7- 0.8 mm, wider than long. |
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2 E. argyrolepis |
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Plants 20-100 cm; perianth bristles 4(-5), equalling the nut; stylopodium 0.4-0.9 x 0.4-0.8 mm, as wide as long. |
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(9) |
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| 9 (8) |
Vascular bundles in cross section 12-28; spikes 9-25 x 3-5 mm; glumes c. 50 or more, 2.5-3.5 mm. |
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4 E. palustris |
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Vascular bundles in cross section 37-38; spikes 15-30 x 4-7 mm; glumes c. 100, 3.5-4.5 mm. |
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3 E. mitracarpa |
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List of lower taxa
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