(Last Modified On 10/16/2012)
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(Last Modified On 10/16/2012)
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Genus
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PASPALUM
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PlaceOfPublication
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Syst. Nat. ed. 10. 2:855. 1759.
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Description
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Spikelets plano-convex, solitary or in pairs, arranged in two rows on one side of a narrow wingless to broadly winged rachis, the back of the fruit turned toward the rachis; first glume wanting or present on some, occasionally on all of the spikelets; second glume and sterile lemma equal, covering the fruit, or the glume a little shorter, rarely wanting; fruit indurate, usually pale, sometimes dark brown, smooth and shining or minutely striate, the margins of the lemma inrolled, en- closing the palea.
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Note
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Annuals or perennials with one to many racemes, these solitary, paired, or racemose at the summit of the main culm and branches.
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Key
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a. Inflorescence feathery, composed of numerous, very slender, drooping racemes, crowded on a short axis --- 39. P. SACCHAROIDES aa. Inflorescence not feathery, the racemes, if hairy, not long, slender, and drooping. b. Rachis winged, with broad membranaceous margins, or if narrowly winged, the spikelets conspicuously fringed with long hairs. c. Plants terrestrial; spikelets conspicuously silky or fringed with long hairs. d. Spikelets 2.5-3.2 mm. long; second glume wingless; sterile lemma inconspicuously fringed. e. Racemes solitary or sometimes paired, the rachis 5-7 mm. wide; culms simple -----1. P. STELLATUM ee. Racemes 2-7, sometimes solitaryon the branches, never paired, the rachis 2-4 mm. wide; culms usually branching. f. Blades 2-3.5 mm. wide, flat or becoming involute; racemes 1-6 cm. long, the rachis 3-4 mm. wide; culms slender, erect - -- 2. P. HETEROTRICHON ff. Blades 6-15 mm. wide, flat; racemes 5-10 cm. long, the rachis 2-3 mm. wide; culms relatively coarse, decumbent at the somewhat woody base - 3. P. HUMBOLDTIANUM dd. Spikelets 4.5-6 mm. long; second glume broadly winged; sterile lemma fringed with long hairs. e. Rachis narrower than the spikelets; glume cordate at base; fruit ciliate ----- ---- 4. P. PECTINATUM ee. Rachis wider than the spikelets; glume not cordate at the base; fruit glabrous - - _ - __ 5. P. CONTRACTUM cc. Plants aquatic; spikelets glabrous. d. Second glume well developed; spikelets 1.4-2 mm. long, elliptic, acute, in two rows, numerous on each raceme - 6. P. REPENS dd. Second glume wanting; spikelets 2.3-2.5 mm. long, oblong, obtuse, appearing as if in a single row, relatively few on each raceme _ - _ ---7. P. CANDIDUM bb. Rachis wingless, or if narrowly winged, the spikelets not conspicu- ously silky or fringed with long hairs. c. Racemes 2, conjugate or nearly so at the summit of the culm, rarely a third one a short distance below. d. Plants extensively stoloniferous. e. Spikelets 1.4-2.2 mm. long, ovate, sparsely long-ciliate around the margins -----26. P. CONJUGATUM ee. Spikelets 3-4.5 mm. long, glabrous. Sea-coast plants - 8. P. VAGINATUM dd. Plants cespitose or rhizomatous, but not stoloniferous. e. Plants perennial; spikelets 2 mm. long or more. f. Spikelets 2-3.8 mm. long, ovate to obovate, or, if elliptic, pubescent. g. Rhizomes stout, horizontal, forming a tough sod; spike- lets glabrous. h. Spikelets 2.5-3.8 mm. long, ovate to obovate, smooth and shining ---- 9. P. NOTATUM hh. Spikelets 2-2.5 mm. long, oval, less shining than the preceding _ ----- 1 0. P. MINUS gg. Rhizomes short; spikelets pubescent - - _ 11. P. SUBCILIATUM ff. Spikelets 4-4.5 mm. long, elliptic, glabrous, with a short tuft of hairs on either side at the base. Base of plant usually covered with old shredded sheaths --- 12. P. LINEARE ee. Plants annual; spikelets 1.1-1.5 mm. long. f. Spikelets subhemispheric, solitary, beaded with globular hairs, rarely glabrous - -- 18. P. MULTICAULE ff. Spikelets elliptic or obovate, paired, pubescent with capitate hairs - - _ _ _ - _ ----- 19. P. CLAVULIFERUM cc. Racemes 1-many, racemose or fascicled on the axis, not conjugate. d. Second glume wanting. Pedicels bearing stiff hairs at least as long as the spikelet _ - _ ---37. P. GARDNERIANUM dd. Second glume well developed. e. First glume present on at least one of a pair of spikelets (see also P. fasciculatum, a coarse aquatic). f. Plants decumbent, creeping; spikelets not more than 2 mm. long. g. First glume about equally developed on all spikelets 14. P. DECUMBENS gg. First glume wanting, or occasionally developed, especially on the secondary spikelet _ - _ - _ 15. P. NUTANS ff. Plants erect; spikelets 2.6-3 mm. long - _ 16. P. PILOSUM ee. First glume wanting, or occasionally developed on some of the spikelets. f. Racemes terminal and axillary, the axillary sometimes hid- den in the sheaths. g. Culms decumbent, rooting at the lower nodes; first glume occasionally developed - ---- 15. P. NUTANS gg. Culms erect; first glume always wanting - --- 13. P. PROPINQUUM ff. Racemes terminal only on the main culm and branches. g. Plants annual. h. Spikelets with a broad firm notched margin --- 38. P. FIMBRIATUM hh. Spikelets without a broad notched margin. i. Fruit pale; spikelets not more than 1.5 mm. long. j. Spikelets 0.8 mm. long, oblong-elliptic, glabrous, with raised margins; rachis zigzag --- 20. P. PARVIFLORUM jj. Spikelets 1.1-1.6 mm. long, hemispherical or elliptic, sparsely to densely covered with globular or capitate hairs. k. Blades 6-20 mm. wide; racemes 6-35, scattered on a long axis - -- -- 22. P. MICROSTACHYUM kk. Blades not more than 2.5 mm. wide; racemes 1 or 2. l. Spikelets subhemispheric, solitary, beaded with globular hairs, rarely glabrous - 18. P. MULTICAULE ll. Spikelets elliptic or obovate, paired, pubes- cent with capitate hairs - - 19. P. CLAVULIFERUM ii. Fruit dark brown, smooth and shining. j. Spikelets suborbicular, or if obovate, 2.2-3 mm. long. k. Culms slender, mostly 20-40 cm. high, decumbent-spreading; racemes 1-4, the rachis 1-2 mm. wide; sheaths and blades usually rather conspicuously papillose-pilose -34. P. CONVEXUM kk. Culms mostly stout, commonly 40-60 cm. high; racemes commonly 4-11, the rachis 2- 2.5 mm. wide; sheaths and blades glabrous or nearly so _ - __ - _ 35. P. BOSCIANUM jj. Spikelets obovate, 2 mm. long ------- 36. P. MELANOSPERMUM gg. Plants perennial. h. Culms creeping, rooting at the lower nodes. Spikelets solitary, not more than 1.8 mm. long. i. Spikelets suborbicular. j. Blades 1-6 cm. long; spikelets 1-1.2 mm. long. Plants stoloniferous- 23. P. ORBICULATUM jj. Blades 5-13 cm. long; spikelets 1.7-1.8 mm. long. Subaquatic -25. P. HITCHCOCKII ii. Spikelets ovate to more or less elliptic, acutish-- 24. P. JIMENEZII hh. Culms not creeping, if rooting at the lower nodes the spikelets in pairs or more than 4 mm. long. i. Plants stoloniferous, coarse, succulent; spikelets 4- 4.5 mm. long, solitary. Racemes usually numerous, arranged in a dense flabellate inflorescence - 27. P. FASCICULATUM ii. Plants not stoloniferous, erect; spikelets not more than 3.9 mm. long, usually much less. j. Fruit dark brown, smooth and shining. k. Sterile lemma wrinkled just within the margins. 32. P. PLICATULUM kk. Sterile lemma flat- 33. P. CENTRALE ji. Fruit pale to stramineous, or if brown not shining, striate-roughened. k. Spikelets 1.3-1.6 mm. long; culms usually slender. l. Racemes 7-60, the lower ones 4-12 cm. long; culms 0.3-2 m. high; spikelets subhemispherical, 1.3-1.5 mm. long, pubescent -17. P. PANICULATUM ll. Racemes 2-4, 2.2-4 cm. long; culms 20-27 cm. high; spikelets narrowly obovate or elliptic, 1.6 mm. long; glabrous - 21. P. STANDLEYI kk. Spikelets 1.9 mm. long or more; culms coarse and robust, mostly 1-2 m. high. 1. Culms freely branching at maturity. Spike- lets elliptic, glandular-pubescent, 2-2.5 mm. long - -- 31. P. CORYPHAEUM 11. Culms simple or with a few simple branches. m. Spikelets obovate or suborbicular, 1.9-3 mm. long. n. Racemes 50-100, crowded; spikelets 1.9-2.2 mm. long, glabrous; fruit pale 30. P. DENSUM nn. Racemes less than 30, commonly 10-16; spikelets 2.2-3 mm. long; fruit dark brown - -- 28. P. VIRGATUM mm. Spikelets elliptic, acute, 3.5-3.9 mm. long. Second glume ciliate on the mar- gins toward the summit, otherwise glabrous..................29. P. ACUTUM
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