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early bluegrass

Diablo bluegrass, Diablo Canyon blue grass

Habit Plants perennial; loosely tufted or with solitary shoots, shortly rhizomatous. Plants perennial; loosely tufted, forming airy mounds to 30 cm across, shortly rhizomatous and stoloniferous.
Culms

15-60 cm, erect or the bases decumbent, not branching above the base, terete or weakly compressed;

nodes terete, 0-1 exserted.

26-50 cm tall, 0.5-0.9 mm thick, bases decumbent or nearly erect, frequently branching above the base, terete or weakly compressed;

nodes terete, 1-2 exserted.

Sheaths

closed for about 1/2 their length, slightly compressed, distinctly keeled, glabrous, bases of basal sheaths glabrous, distal sheath lengths 4-60 times blade lengths;

collars of proximal leaves usually retrorsely scabrous or pubescent distally and about the throat;

ligules 0.5-4 mm, smooth or scabrous, apices truncate to acute;

innovation blades similar to the cauline blades;

cauline blades 1-4 mm wide, usually flat, sometimes slightly folded, smooth or sparsely scabrous, primarily over the veins, apices broadly prow-shaped, blades steeply reduced in length distally, flag leaf blades 0.2-3(6) cm.

closed for 2/5 – 7/10 their length, weakly keeled, sparsely scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 0.6-2.4 times blade lengths;

collars scabrous or pubescent on the margins;

ligules (1)2-3 mm, moderately densely scabrous, truncate, obtuse, or acute, lacerate to entire;

innovation blades to 20 cm, adaxial surfaces sparsely scabrous, glabrous or hispidulous on and between the veins;

cauline blades 1.5-2.4 mm wide, folded or flat, thin, soft, abaxial surfaces smooth, veins prominent, keel and margins scabrous, adaxial surfaces moderately scabrous over the veins, sparsely scabrous between the veins, apices narrowly prow-shaped, flag leaf blades 2.9-8.6(11) cm.

Basal branching

mainly extravaginal.

extra-, pseudo-, and intravaginal.

Panicles

5-15 cm, erect or lax, pyramidal, open, sparse, with 20-80 spikelets, proximal internodes usually 3+ cm;

nodes usually with 2 branches;

branches (2)3-7(10) cm, spreading to reflexed, straight, angled, angles scabrous, with 2-8(10) spikelets.

(4)5.5-10.5(12.5) cm, erect, ovoid to broadly pyramidal, open, or eventually loosely contracted, sparse, with 10-40 spikelets;

nodes with 1-2 branches;

branches 2.1-4.5(7) cm, ascending, lax, angled, angles moderately to densely scabrous, less scabrous between the angles, with 1-9 spikelets.

Spikelets

5-8 mm, lengths to 3.5 times widths, laterally compressed, not sexually dimorphic;

florets 2-5;

rachilla internodes smooth.

5.3-9 mm, lengths to 3 times widths, laterally compressed, not sexually dimorphic;

florets (2)3-6(7);

rachilla internodes 1-1.3 mm, visible from the sides, usually sparsely to densely, coarsely scabrous, infrequently smooth.

Glumes

narrowly lanceolate to lanceolate, distinctly keeled;

lower glumes 1-3-veined;

calluses webbed, hairs over 1/3 the lemma length;

lemmas 3-6 mm, lanceolate, distinctly keeled, keels and marginal veins sparsely short- to long-villous, lateral veins moderately prominent, intercostal regions glabrous or the upper florets in the spikelets softly puberulent, margins glabrous, apices acute;

palea keels scabrous, softly puberulent at midlength;

anthers vestigial (0.1-0.2 mm) or 2-3.5 mm.

distinctly keeled;

lower glumes (2)2.7-3.8 mm, 3-veined, upper glumes (2.3)2.9-3.9 mm;

calluses diffusely webbed, hairs 1/3-1/2 the lemma length;

lemmas (3.2)4.25-5 mm, lanceolate to narrowly lanceolate, distinctly keeled, glabrous, moderately to densely, infrequently sparsely, scabrous, lateral veins prominent, margins narrowly scarious, glabrous, apices acute to narrowly acute;

paleas 3/4 as long as to subequal to the lemmas, keels scabrous, intercostal regions scabrous;

anthers (1.4)1.75-2.6 mm, or vestigial (0.1-0.2 mm).

2n

= 28.

= unknown.

Poa cuspidata

Poa diaboli

Distribution
from FNA
AL; DC; DE; GA; IN; KY; LA; MD; NC; NJ; NY; OH; PA; SC; TN; VA; WV
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[BONAP county map]
[BONAP county map]
Discussion

Poa cuspidata is a common species of forest openings in the Appalachian Mountains. It is an eastern counterpart of P. arnowiae (see previous), P. tracyi (p. 543), and P. nervosa (see next). Like those species, it is sequentially gynomonoecious.

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

Poa diaboli, which is sequentially gynomonoecious, is endemic to upper shaly slopes, in soft coastal scrub and openings in Bishop Pine stands, in the coastal mountains of San Luis Obispo County, California. It is closely related to P. confinis (see previous), from which it differs by a suite of characters. The two species are also ecologically and geographically distinct.

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

Source FNA vol. 24, p. 545. FNA vol. 24, p. 552.
Parent taxa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Poa Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Madropoa
Sibling taxa
P. abbreviata, P. alpina, P. alsodes, P. ammophila, P. annua, P. arachnifera, P. arctica, P. arida, P. arnowiae, P. atropurpurea, P. autumnalis, P. bigelovii, P. bolanderi, P. bulbosa, P. chaixii, P. chambersii, P. chapmaniana, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. diaboli, P. douglasii, P. eminens, P. fendleriana, P. glauca, P. hartzii, P. howellii, P. infirma, P. interior, P. keckii, P. kelloggii, P. laxa, P. laxa × glauca, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. macrantha, P. macrocalyx, P. marcida, P. napensis, P. nemoralis, P. nervosa, P. occidentalis, P. paludigena, P. palustris, P. paucispicula, P. piperi, P. porsildii, P. pratensis, P. pringlei, P. pseudoabbreviata, P. reflexa, P. rhizomata, P. saltuensis, P. secunda, P. sierrae, P. stebbinsii, P. stenantha, P. strictiramea, P. sublanata, P. suksdorfii, P. supina, P. sylvestris, P. tenerrima, P. tracyi, P. trivialis, P. unilateralis, P. wheeleri, P. wolfii, P. ×gaspensis, P. ×limosa, P. ×nematophylla
P. abbreviata, P. alpina, P. alsodes, P. ammophila, P. annua, P. arachnifera, P. arctica, P. arida, P. arnowiae, P. atropurpurea, P. autumnalis, P. bigelovii, P. bolanderi, P. bulbosa, P. chaixii, P. chambersii, P. chapmaniana, P. compressa, P. confinis, P. curtifolia, P. cusickii, P. cuspidata, P. douglasii, P. eminens, P. fendleriana, P. glauca, P. hartzii, P. howellii, P. infirma, P. interior, P. keckii, P. kelloggii, P. laxa, P. laxa × glauca, P. laxiflora, P. leibergii, P. leptocoma, P. lettermanii, P. macrantha, P. macrocalyx, P. marcida, P. napensis, P. nemoralis, P. nervosa, P. occidentalis, P. paludigena, P. palustris, P. paucispicula, P. piperi, P. porsildii, P. pratensis, P. pringlei, P. pseudoabbreviata, P. reflexa, P. rhizomata, P. saltuensis, P. secunda, P. sierrae, P. stebbinsii, P. stenantha, P. strictiramea, P. sublanata, P. suksdorfii, P. supina, P. sylvestris, P. tenerrima, P. tracyi, P. trivialis, P. unilateralis, P. wheeleri, P. wolfii, P. ×gaspensis, P. ×limosa, P. ×nematophylla
Name authority Nutt. Soreng & D.J. Keil
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