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Springfield bluestem, Springfield's beardgrass

beardgrass

Habit Plants perennial; cespitose or stoloniferous.
Culms

30-80 cm, erect, unbranched;

nodes prominently bearded, hairs 3-7 mm, spreading, silvery-white.

30-250 cm, with pithy internodes.

Leaves

mostly basal;

ligules 1-2.5 mm;

blades 5-30 cm long, 2-3(5) mm wide, flat to folded, glabrous or sparsely hispid adaxially, pilose near the throat.

basal or cauline, not aromatic;

sheaths open;

auricles absent;

ligules membranous, sometimes also ciliate;

blades usually flat, convolute in the bud.

Panicles

4-9 cm, oblong to fan-shaped;

rachises 1-5 cm, with 2-9 branches;

branches 4-8 cm, longer than the rachises, with 1(2) rames;

rame internodes with a membranous groove wider than the margins, margins densely white-villous, hairs 5-10 mm, obscuring the sessile spikelets.

Inflorescences

terminal, panicles of subdigitate to racemosely arranged branches, each branch with (1)2-many rames, branches not subtended by modified leaves;

rames with spikelets in heterogamous sessile-pedicellate pairs, internodes with a translucent, longitudinal groove, often villous on the margins;

disarticulation in the rames, beneath the sessile spikelets.

Spikelets

dorsally compressed;

sessile spikelets with 2 florets;

lower glumes rounded, several-veined, sometimes with a dorsal pit, margins clasping the upper glume;

upper glumes somewhat keeled, 3-veined;

lower florets hyaline scales, unawned;

upper florets bisexual;

upper lemmas with a midvein that usually extends into a twisted, geniculate awn, occasionally unawned;

anthers 3.

Caryopses

lanceolate to oblong, somewhat flattened;

hila punctate, basal;

embryos about Yi as long as the caryopses.

Pedicels

similar to the internodes.

Sessile

spikelets 5.5-8.5 mm, lanceolate;

lower glumes densely short-pilose on the lower M, sometimes with a dorsal pit;

awns 18-26 mm;

anthers 1-1.5 mm.

Pedicellate

spikelets 3.5-5.5 mm, sterile.

spikelets reduced or well-developed, sterile or staminate, unawned.

x

= 10.

2n

= 120.

Bothriochloa springfieldii

Bothriochloa

Distribution
from FNA
AZ; CO; LA; NM; TX; UT
[BONAP county map]
from FNA
AL; AR; AZ; CA; CO; FL; GA; IL; IN; KS; KY; LA; MD; MO; MS; NE; NM; NV; NY; OH; OK; SC; TN; TX; UT; HI; PR; Virgin Islands
[BONAP county map]
Discussion

Bothriochloa springfieldii grows in rocky uplands, ravines, plains, sandy areas, and roadsides, from southern Utah to western Texas and Mexico at 900-2500 m. and, as a disjunct in northwest Louisiana. It differs from B. barbinodis in its less robust habit, narrower blades, longer nodal hairs, and fewer, more hairy panicle branches, and from B. edwardsiana in its pubescent nodes and wider, non-ciliate leaf blades.

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

Bothriochloa is a genus of about 35 species that grow in tropical to warm-temperate regions. Nine are native to the Flora region; three Eastern Hemisphere species have been introduced into the southern United States for forage and range rehabilitation. Most species provide fair forage in summer and fall. Polyploidy has been an important mechanism of speciation in the genus.

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

Key
1. Pedicellate spikelets about as long as the sessile spikelets.
→ 2
2. Sessile spikelets 5.5-7 mm long
B. wrightii
2. Sessile spikelets 3-4.5 mm long.
→ 3
3. Rachises longer than the branches
B. bladhii
3. Rachises shorter than the branches.
→ 4
4. Lower glumes of the sessile spikelets with a dorsal pit
B. pertusa
4. Lower glumes of the sessile spikelets without a dorsal pit
B. ischaemum
1. Pedicellate spikelets much shorter than the sessile spikelets.
→ 5
5. Sessile spikelets 2.5-4.5 mm long; awns absent or less than 17 mm long.
→ 6
6. Sessile spikelets unawned or with awns less than 6 mm long
B. exaristata
6. Sessile spikelets with awns 8-17 mm long.
→ 7
7. Panicles reddish when mature; hairs below the sessile spikelets about 1/4 as long as the spikelets, sparse, not obscuring the spikelets
B. bladhii
7. Panicles silvery-white or light tan; hairs below the sessile spikelets at least 1/2 as long as the spikelets, copious, at least somewhat obscuring the spikelets.
→ 8
8. Panicles 9-20 cm long; sessile spikelets narrowly ovate to lanceolate; glumes acute; leaves evenly distributed on the culms; culms 2-4 mm thick
B. longipaniculata
8. Panicles 4-12(14) cm long; sessile spikelets ovate; glumes blunt; leaves often clustered at the base of the culms; culms usually less than 2 mm thick
B. laguroides
5. Sessile spikelets 4.5-8.5 mm long; awns 18-35 mm long.
→ 9
9. Rachises 5-20 cm long, with numerous branches.
→ 10
10. Panicles of the larger shoots 14-25 cm long; culms 130-250 cm tall, 2-4 mm thick, stiffly erect, little-branched distally, glaucous below the nodes; nodes with spreading hairs, the hairs 2-6 mm long
B. alta
10. Panicles of the larger shoots 5-14(20) cm long; culms usually 60-120 cm tall, usually less than 2 mm thick, tending to be bent at the base and often branched at maturity, not glaucous below the nodes; nodes with ascending hairs less than 3 mm long
B. barbinodis
9. Rachises usually less than 5 cm long, with 2-9 branches.
→ 11
11. Cauline nodes densely pubescent, the hairs 3-7 mm long, white, spreading
B. springfieldii
11. Cauline nodes glabrous or puberulent, the hairs always less than 3 mm long, usually off-white and ascending.
→ 12
12. Lower branches of the inflorescences rebranched; sessile spikelets 4.5-6.5 mm long; lower glumes sparsely hairy near the base; leaves primarily cauline, the blades 2-5 mm wide
B. hybrida
12. Lower branches of the inflorescences simple, not rebranched; sessile spikelets 5-8 mm long; lower glumes glabrous; leaves primarily basal, the blades usually less than 2 mm wide
B. edwardsiana
Source FNA vol. 25, p. 644. FNA vol. 25, p. 639. Author: Kelly W. Allred;.
Parent taxa Poaceae > subfam. Panicoideae > tribe Andropogoneae > Bothriochloa Poaceae > subfam. Panicoideae > tribe Andropogoneae
Sibling taxa
B. alta, B. barbinodis, B. bladhii, B. edwardsiana, B. exaristata, B. hybrida, B. ischaemum, B. laguroides, B. longipaniculata, B. pertusa, B. wrightii
Subordinate taxa
B. alta, B. barbinodis, B. bladhii, B. edwardsiana, B. exaristata, B. hybrida, B. ischaemum, B. laguroides, B. longipaniculata, B. pertusa, B. springfieldii, B. wrightii
Synonyms Andropogon springfieldii
Name authority (Gould) Parodi Kuntze
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