Andropogon gerardii |
Andropogon |
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Barbon de Gerard, big bluestem |
bluestem |
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Habit | Plants often forming large clumps, rhizomes, if present, with internodes shorter than 2 cm. | Plants perennial; usually cespitose, sometimes rhizomatous. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Culms | 1-3 m, often glaucous. |
20-310 cm, erect, much-branched distally. |
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Sheaths | glabrous or pilose; ligules 0.4-2.5 mm; blades 5-50 cm long, (2)5-10 mm wide, usually pilose adaxially, at least near the collar. |
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Leaves | not aromatic; ligules membranous, sometimes ciliate; blades linear, flat, folded, or convolute. |
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Inflorescences/ |
usually only terminal; peduncles with 2-6(10) rames; rames 5-11 cm, exserted at maturity, usually purplish, sometimes yellowish; internodes sparsely to densely pubescent, hairs 2.2-4.2 mm, usually white, rarely yellowish. |
terminal and axillary or a false panicle; inflorescence units 1-600+ per culm; peduncles initially concealed by the subtending leaf sheaths, sometimes exserted beyond the sheaths at maturity, with (1)2-5(13) rames; rames not reflexed at maturity, axes slender, terete to flattened, not longitudinally grooved, usually conspicuously pubescent, with spikelets in heterogamous sessile-pedicellate pairs (the terminal spikelets sometimes in triplets of 1 sessile and 2 pedicellate spikelets), apices of the internodes neither cupulate nor fimbriate; disarticulation in the rames, below the sessile spikelets. |
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Pedicels | usually longer than 3 mm, similar to the rame internodes in shape, length, and pubescence color, not fused to the rame axes. |
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Sessile | spikelets 5-11 mm, scabrous; awns 8-25 mm; anthers 3, 2.5-4.5 mm. |
spikelets bisexual, awned, with short, blunt calluses; lower glumes 2-keeled, flat or concave, usually not veined between the keels, sometimes 2-9-veined; anthers 1, 3(2). |
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Pedicellate | spikelets 3.5-12 mm, usually well-developed and staminate. |
spikelets usually vestigial or absent, sometimes well-developed and staminate. |
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x | = 10. |
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2n | = 20, 40, 60 (usually), 70, 80. |
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Andropogon gerardii |
Andropogon |
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Distribution |
AL; AR; AZ; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NY; OH; OK; PA; RI; SC; SD; TN; TX; UT; VA; VT; WI; WV; WY; MB; ON; QC; SK
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AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; PA; RI; SC; SD; TN; TX; UT; VA; VT; WI; WV; WY; HI; PR; MB; ON; QC; SK; Virgin Islands |
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Discussion | Andropogon gerardii grows in prairies, meadows, and generally dry soils. It is a widespread species, extending from southern Canada to Mexico, and was once dominant over much of its range. It is frequently planted for erosion control, restoration, or as an ornamental; the records from Washington and central Montana reflect such plantings. It hybridizes with A. ballii, the two sometimes being treated as conspecific subspecies. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Andropogon is a cosmopolitan genus of tropical and temperate zones, comprising approximately 120 species. Thirteen species are native to the Flora region. Andropogon bicornis has been found in the region but is not known to be established. All but A. hallii grow in the southeastern United States. Several taxa are ecologically important in North America. Andropogon gerardii is one of the most important native grasses in North America, being one of the dominant species in the tall-grass prairies that used to cover the center of the continent. Many varieties of A. glomeratus and A. virginicus aggressively colonize abandoned fields, cutover timberlands, and roadsides. Some species are used in restoration and landscaping. Species of Andropogon with solitary rames are easily confused with Schizachyrium but, in Andropogon, the lower glumes of the sessile spikelets are flat or concave and the rame internodes are not cupulate, whereas Schizachyrium has convex glumes and rame internodes with strongly cupulate apices. Successful identification of species in Andropogon sect. Leptopogon (numbers 3-14) requires mature, complete specimens and careful field study (Campbell 1983, 1986). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 25, p. 653. | FNA vol. 25, p. 649. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Parent taxa | Poaceae > subfam. Panicoideae > tribe Andropogoneae > Andropogon > sect. Andropogon | Poaceae > subfam. Panicoideae > tribe Andropogoneae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Synonyms | A. provincialis, A. furcatus | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Name authority | Vitman | L. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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