Poa cusickii |
Poa diaboli |
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Cusick's bluegrass |
Diablo bluegrass, Diablo Canyon blue grass |
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Habit | Plants perennial; usually densely tufted, rarely moderately densely tufted, usually neither rhizomatous nor stoloniferous, infrequently short-rhizomatous or stoloniferous, rarely with distinct rhizomes. | Plants perennial; loosely tufted, forming airy mounds to 30 cm across, shortly rhizomatous and stoloniferous. | ||||||||||||
Culms | 10-60(70) cm tall, 0.5-1.8 mm thick, erect or the bases decumbent, terete or weakly compressed; nodes terete, 0-2 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. |
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Sheaths | closed for 1/4-3/4 their length, terete, smooth or scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 1.6-10 times blade lengths; collars smooth or scabrous, glabrous; ligules of cauline leaves 1-3(6) mm, smooth or scabrous, truncate to acute, ligules of the innovation leaves 0.2-0.5(2.5) mm, scabrous, usually truncate; innovation blades sometimes distinctly different from the cauline blades, 0.5-2 mm wide, involute, moderately thick, moderately firm, adaxial surfaces usually densely scabrous or hispidulous to softly puberulent, infrequently nearly smooth and glabrous; cauline blades subequal or the midcauline blades longest or the blades gradually reduced in length distally, 0.5-3 mm wide, flat, folded, or involute, usually thin, usually withering, abaxial surfaces smooth or scabrous, apices narrowly to broadly prow-shaped, flag leaf blades 0.5-5(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. |
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Basal branching | intravaginal or intra- and extravaginal. |
extra-, pseudo-, and intravaginal. |
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Panicles | 2-10(12) cm, usually erect, contracted or loosely contracted, narrowly lanceoloid to ovoid, congested or moderately congested, with 10-100 spikelets and 1-3(5) branches per node; branches 0.5-4(5) cm, erect or steeply ascending, fairly straight, slender to stout, terete to angled, smooth or scabrous, with 1-15 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. |
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Spikelets | (3)4-10 mm, lengths to 3 times widths, broadly lanceolate to narrowly ovate, laterally compressed, not sexually dimorphic; florets 2-6; rachilla internodes 0.5-1.2 mm, smooth or scabrous. |
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. |
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Glumes | lanceolate, distinctly keeled; lower glumes 3-veined, distinctly shorter than the lowest lemmas; calluses glabrous or diffusely webbed, hairs less than 1/4 the lemma length; lemmas (3)4-7 mm, lanceolate to broadly lanceolate, distinctly keeled, membranous to thinly membranous, smooth or sparsely to densely scabrous, glabrous or the keels and/or marginal veins puberulent proximally, lateral veins obscure to prominent, margins glabrous, apices acute; palea keels scabrous, intercostal regions glabrous; anthers vestigial (0.1-0.2 mm), aborted late in development, 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). |
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2n | = 28, 28+11, 56, 56+11, 59, ca. 70. |
= unknown. |
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Poa cusickii |
Poa diaboli |
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Distribution |
CA; CO; ID; MT; ND; NV; OR; UT; WA; WY; AB; BC; MB; SK; YT
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Discussion | Poa cusickii grows in rich meadows in sagebrush scrub to rocky alpine slopes, from the southwestern Yukon Territory to Manitoba and North Dakota, south to central California and eastern Colorado. It is gynodioecious or dioecious. Sexually reproducing plants of Poa cusickii subspp. cusickii and pallida grow in different geographic areas, but pistillate plants of these two subspecies have overlapping ranges. Only pistillate plants are known in Poa cusickii subspp. epilis and purpurascens. All the alpine plants studied were pistillate. (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.) |
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Key |
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Source | FNA vol. 24, p. 559. | FNA vol. 24, p. 552. | ||||||||||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Epiles | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Madropoa > subsect. Madropoa | ||||||||||||
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Name authority | Vasey | Soreng & D.J. Keil | ||||||||||||
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