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Barbon de Gerard, big bluestem

bushy beardgrass, bushy bluestem

Habit Plants often forming large clumps, rhizomes, if present, with internodes shorter than 2 cm. Plants cespitose, upper portion dense, oblong to oblanceolate or obpyramidal.
Culms

1-3 m, often glaucous.

20-250 cm;

internodes green, sometimes glaucous;

branches mostly erect, straight.

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.

usually scabrous, sometimes smooth;

ligules 0.6-2.2 mm, sometimes ciliate, cilia to 0.9 mm;

blades 13-109 cm long, 2.9-9.5 mm wide, glabrous or sparsely to densely pubescent, hairs usually spreading, rarely appressed.

Inflorescence units

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.

10-600 per culm; subtending sheaths (2.0)2.9-4.4(6.5) cm long, (1.5)2.3-3.4(4.4) mm wide;

peduncles (1)6-14(60) mm, with 2(4) rames;

rames (1)1.7-2.5(3.5) cm, exserted or not at maturity, pubescence sparse basally and increasing in density distally within each internode.

Sessile

spikelets 5-11 mm, scabrous;

awns 8-25 mm;

anthers 3, 2.5-4.5 mm.

spikelets 3-5 mm;

callus hairs 1-2.5 mm;

keels of lower glumes sometimes scabrous below midlength, usually scabrous distally;

awns 6-19 mm;

anthers 1(3), 0.5-1.5 mm, yellow, red, or purple.

Pedicellate

spikelets 3.5-12 mm, usually well-developed and staminate.

spikelets vestigial or absent, sterile.

2n

= 20, 40, 60 (usually), 70, 80.

= 20.

Andropogon gerardii

Andropogon glomeratus

Distribution
from FNA
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
[WildflowerSearch map]
from FNA
AL; AR; AZ; CA; DC; DE; FL; GA; IL; KY; LA; MA; MD; MS; NC; NJ; NM; NV; NY; OH; OK; PA; RI; SC; TN; TX; UT; VA; WV; HI; PR; Virgin Islands
[WildflowerSearch map]
[BONAP county map]
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 glomeratus hybridizes with both A. longiberbis and A. virginicus. Some of its varieties are morphologically similar to the latter species.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Blades glaucous, glabrous, and smooth
var. glaucopsis
1. Blades green, often pubescent or scabrous
→ 2
2. Sheaths subtending the inflorescence units 1.5-3 mm wide; leaf sheaths usually smooth; ligules ciliate, the cilia 0.2-0.9 mm long
var. pumilus
2. Sheaths subtending the inflorescence units (1.5)2.3-3.4(4.4) mm wide; leaf sheaths often scabrous; ligules, when ciliate, with the cilia no more than 0.5 mm long.
→ 3
3. Keels of the lower glumes scabrous below and beyond midlength
var. scabriglumis
3. Keels of the lower glumes usually smooth below midlength, scabrous distally.
→ 4
4. Upper portion of the plants oblong to obpyramidal; mature peduncles (4)11-35(60) mm long; anthers eventually falling
var. glomeratus
4. Upper portion of the plants cylindrical to oblong; mature peduncles 2-5 (8) mm long; withered remnants of anthers retained within the spikelets
var. hirsutior
Source FNA vol. 25, p. 653. FNA vol. 25, p. 661.
Parent taxa Poaceae > subfam. Panicoideae > tribe Andropogoneae > Andropogon > sect. Andropogon Poaceae > subfam. Panicoideae > tribe Andropogoneae > Andropogon > sect. Leptopogon
Sibling taxa
A. arctatus, A. bicornis, A. brachystachyus, A. floridanus, A. glomeratus, A. gracilis, A. gyrans, A. hallii, A. liebmannii, A. longiberbis, A. ternarius, A. tracyi, A. virginicus
A. arctatus, A. bicornis, A. brachystachyus, A. floridanus, A. gerardii, A. gracilis, A. gyrans, A. hallii, A. liebmannii, A. longiberbis, A. ternarius, A. tracyi, A. virginicus
Subordinate taxa
A. glomeratus var. glaucopsis, A. glomeratus var. glomeratus, A. glomeratus var. hirsutior, A. glomeratus var. pumilus, A. glomeratus var. scabriglumis
Synonyms A. provincialis, A. furcatus
Name authority Vitman (Walter) Britton, Sterns & Poggenb.
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