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needle grama

buffalograss, grama

Habit Plants annual; tufted. Plants annual or perennial; synoecious; habit various, cespitose, stoloniferous, or rhizomatous.
Culms

4-60 cm, outer culms of a tuft decumbent, sometimes geniculate, branched at the lower nodes.

1-80 cm.

Leaves

usually mostly basal;

sheaths open;

ligules of hairs, membranous, or membranous and ciliate.

Panicles

2.5-10.5 cm, with (1)4-15 branches;

branches 5-45 mm, deciduous, densely pubescent (at least basally), with 2-10 spikelets per branch, axes extending 2-10 mm beyond the base of the terminal spikelets, apices entire;

disarticulation at the base of the branches, the break forming a sharp tip.

Inflorescences

terminal, panicles of 1-80 solitary, spikelike branches, exceeding the upper leaves;

branches 4-50(75) mm, not woody, 1-sided, usually racemose on elongate rachises, sometimes digitate or subdigitate, with 1-130+ sessile to subsessile spikelets in 2 rows, axes terminating in a spikelet or extending beyond the base of the distal spikelet.

Spikelets

appressed.

closely imbricate, appressed to pectinate, laterally compressed or terete, with 1-2(3) florets, lowest floret in each spikelet bisexual, distal florets staminate or sterile;

disarticulation at the base of the branches or above the glumes.

Glumes

unequal or subequal, 1 or both glumes equaled or exceeded by the distal floret, 1-veined, acute or acuminate, sometimes shortly awned;

lower glumes usually shorter than the lowest floret;

lemmas of lowest florets entire, bilobed, trilobed, or 4-lobed, 3-veined, veins usually extended into 3 short awns;

paleas of lowest florets 2-veined, veins sometimes excurrent;

distal floret(s) staminate or sterile, varying from similar to the lowest floret in shape, size, and venation to sterile and reduced to an awn column with well-developed awns or to a flabellate scale, x = 10.

Caryopses

2.5-3 mm.

Ligules

0.2-0.5 mm, membranous, lacerate or ciliate;

blades 2-5(9) cm long, 0.7-2 mm wide, flat or folded, adaxial surfaces sometimes with papillose-based hairs, margins usually with papillose-based hairs near the ligules.

Proximal

spikelet on each branch with 1 floret;

lower glumes 1.5-3.5 mm, glabrous, narrow to subulate;

upper glumes 5.5-6.2 mm, densely pubescent, at least on the basal 1/2;

lemmas 5.8-6 mm, acuminate, unawned;

lowest paleas almost as long as the lemmas, bifid, glabrous;

rachillas prolonged beyond the florets for about 0.5 mm.

Distal

spikelets with 1 bisexual and 1 rudimentary floret, glumes unequal, glabrous, minutely scabrous on the keels; narrowly acute or acuminate;

lower glumes 1.5-2 mm;

upper glumes 5-6 mm, glabrous or sparsely pubescent basally, often divergent;

lowest lemmas 6-8 mm, veins pubescent, lateral veins excurrent as short (to 1 mm) awns, acuminate, midvein extended into a setaceous tip or a short awn;

lowest paleas 5-7 mm, bifid, veins often excurrent as short awns;

anthers about 2.5 mm, yellow or yellow and red;

distal florets reduced to a pubescent, 3-awned, awn column, awns 2-7 mm, exserted.

2n

= 40.

Bouteloua aristidoides

Bouteloua

Distribution
from FNA
AZ; CA; MD; NM; NV; TX; UT
[WildflowerSearch map]
[BONAP county map]
from FNA
AL; AR; AZ; CA; CO; CT; DC; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NJ; NM; NV; NY; OH; OK; OR; PA; SC; SD; TN; TX; UT; VA; WA; WI; WV; WY; HI; PR; AB; BC; MB; ON; SK; Virgin Islands
[BONAP county map]
Discussion

There are two varieties, both of which grow in the Flora region.

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

Bouteloua, a genus of the Western Hemisphere with its center of diversity in Mexico, has about 40 species; all 19 species treated here are native to the Flora region. Several of its taxa are important forage grasses, and some are important constituents of the native North American grasslands. Two that are particularly important in North America are Bouteloua curtipendula and B. gracilis. These were major constituents of the shortgrass prairie that once covered the drier portions of the Great Plains. Both are excellent forage species. Irrigation has converted much of the area they once occupided to agricultural use, but large areas of Bouteloua grasslands remain.

Based on molecular data and morphological similarities in the non-pistillate characters, Columbus (1999) recommended expanding Bouteloua to include Buchloë, Opizia, and Cathestecum, plus some other small genera not known from the Flora region. The traditional treatment is adopted here, pending corroboration from a wider range of data, both molecular and morphological.

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

Key
1. Panicle branches with 2-5 spikelets, usually 5-16 mm to the base of the terminal spikelets, axes usually extending an additional 6-10 mm
var. aristidoides
1. Panicle branches with 6-10 spikelets, usually 15-35 mm to the base of the terminal spikelets, axes extending an additional 2-5(7) mm
var. arizonica
1. Panicle branches deciduous, disarticulation occurring at their bases; spikelets usually 1-15 per branch, usually appressed rather than pectinate (subg. Bouteloua).
→ 2
2. All or most panicle branches with 1 spikelet
B. uniflora
2. All or most panicle branches with 2-15 spikelets.
→ 3
3. First (proximal) spikelet on each branch with 1 floret, the remaining spikelets with 2 florets; plants annual; panicles with 1-15 branches
B. aristidoides
3. Spikelets all alike or with 2 or more florets; plants annual or perennial; panicles with 1-80 branches.
→ 4
4. Central awns of lemmas flanked by 2 membranous lobes at maturity, the lobes 0.5-1.5 mm.
→ 5
5. Upper glumes bilobed, awned, the awns arising from between the teeth; inflorescence branch axes with deeply bi- or trifurcate apices; second florets sterile, rudimentary
B. rigidiseta
5. Upper glumes acute, unawned or awn-tipped; inflorescence branch axes with apices entire; second florets usually staminate.
→ 6
6. Base of plants dense, hard and knotty; culms straight, unbranched; panicle branches (15)20-30 mm long; plants rhizomatous
B. radicosa
6. Base of plants usually not dense, hard, or knotty; culms straight or geniculate, branching; panicle branches 10-20 mm long; plants not rhizomatous
B. repens
4. Central awns of lemmas, if present, not flanked by membranous lobes or the lobes less than 0.3 mm long.
→ 7
7. Upper glumes with hairs, at least over the midveins.
→ 8
8. Upper glumes with hairs only over the veins
B. repens
8. Upper glumes with hairs over the veins and elsewhere.
→ 9
9. Panicles 6-10 cm long; branches with 2-6 spikelets
B. eludens
9. Panicles 2.5-6 cm long; branches with 8-12 spikelets
B. chondrosoides
7. Upper glumes glabrous, sometimes scabrous.
→ 10
10. Second florets sterile, usually rudimentary, usually without paleas; central awns rarely to 7 mm long; panicles with 9-80 branches.
→ 11
11. At least some leaf blades more than 2.5 mm wide, flat or folded when dry; ligules 0.3-0.5 mm long; anthers yellow, orange, red, or purple
B. curtipendula
11. Leaf blades 1-1.5(2.5) mm wide, involute when dry; ligules 1-1.5 mm long; anthers dark purple
B. warnockii
10. Second florets bisexual, pistillate or staminate, with well-developed paleas; central awns 4-10 mm long; panicles with 2-17 branches.
→ 12
12. Base of plants dense, hard and knotty; culms straight, unbranched; panicle branches (15)20-30 mm long; plants rhizomatous
B. radicosa
12. Base of plants usually not dense, hard, or knotty; culms straight or geniculate, branching; panicle branches 10-20 mm long; plants not rhizomatous
B. repens
1. Panicle branches persistent; disarticulation above the glumes; spikelets 6-130 or more per branch, pectinate (subg. Chondrosum).
→ 13
13. Upper glumes of at least some spikelets with papillose-based hairs.
→ 14
14. Panicle branches extending beyond the base of the terminal spikelets
B. hirsuta
14. Panicle branches terminating in a spikelet.
→ 15
15. Plants tufted annuals or short-lived stoloniferous perennials; panicle branches 4-8, the axes with papillose-based hairs; lowest lemmas 3-4 mm long
B. parryi
15. Plants perennial, often shortly rhizomatous; panicle branches 1-3(6), the axes scabrous, never with papillose-based hairs; lowest lemmas 3.5-6 mm long
B. gracilis
13. Upper glumes glabrous, scabrous, or hairy, but the hairs not papillose-based.
→ 16
16. Lower cauline internodes woolly-pubescent
B. eriopoda
16. Lower cauline internodes glabrous or mostly so, sometimes pubescent immediately below the nodes.
→ 17
17. Central awns of lemmas not flanked by membranous lobes
B. trifida
17. Central awns of lemmas flanked by 2 membranous lobes.
→ 18
18. Lowest paleas in the spikelets awned, awns 1-2 mm long; panicles with 2-20 branches.
→ 19
19. Lowest lemmas glabrous, with awns 3-4 mm long; panicle branches with 6-20 spikelets; plants perennial
B. kayi
19. Lowest lemmas densely pilose, with awns 0.5-3 mm long; panicle branches with 20-50 spikelets; plants annual or short-lived perennials
B. barbata
18. Lowest paleas in the spikelets unawned, but the veins sometimes excurrent for less than 1 mm; panicles with 1-6 branches.
→ 20
20. Plants annual
B. simplex
20. Plants perennial.
→ 21
21. Culms usually with 2-3 nodes, not woody at the base; caryopses 2.5-3 mm long; lower paleas shallowly bilobed, the veins sometimes excurrent
B. gracilis
21. Culms usually with 4-5 nodes, somewhat woody at the base; caryopses 1-1.2 mm long; lower paleas acute to acuminate, the veins not excurrent.
→ 22
22. Lower culm internodes with a thick, white, chalky bloom distally; panicle branches stramineous, mostly appressed, usually straight to slightly arcuate; plants rhizomatous, growing on gypsum soils
B. breviseta
22. Lower culm internodes without a conspicuous bloom; panicle branches dark, mostly ascending to widely divergent, usually becoming arcuate; plants not rhizomatous, growing on limestone soils
B. ramosa
Source FNA vol. 25, p. 255. FNA vol. 25, p. 250. Author: J.K. Wipff;.
Parent taxa Poaceae > subfam. Chloridoideae > tribe Cynodonteae > Bouteloua > subg. Bouteloua Poaceae > subfam. Chloridoideae > tribe Cynodonteae
Sibling taxa
B. barbata, B. breviseta, B. chondrosoides, B. curtipendula, B. eludens, B. eriopoda, B. gracilis, B. hirsuta, B. kayi, B. parryi, B. radicosa, B. ramosa, B. repens, B. rigidiseta, B. simplex, B. trifida, B. uniflora, B. warnockii
Subordinate taxa
B. aristidoides var. aristidoides, B. aristidoides var. arizonica
B. aristidoides, B. barbata, B. breviseta, B. chondrosoides, B. curtipendula, B. eludens, B. eriopoda, B. gracilis, B. hirsuta, B. kayi, B. parryi, B. radicosa, B. ramosa, B. repens, B. rigidiseta, B. simplex, B. trifida, B. uniflora, B. warnockii
Name authority (Kunth) Griseb. Lag.
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