Poa leptocoma |
Poa cusickii |
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bog bluegrass |
Cusick's bluegrass |
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Habit | Plants perennial, 15–100 cm, often partially purplish, more or less cespitose. | Plants perennial, gynodioecious, or all pistillate, 10–60(70)cm long, usually densely cespitose with short rhizomes. |
Culms | 0.5–1.8 mm thick; nodes terete, 0–2 exserted. |
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Basal branching | mostly extravaginal. |
intravaginal or intra- and extravaginal. |
Leaves | sheaths closed 25–67% of their length; smooth or sparsely scabrous; ligules 1.5– 4(6)mm; blades flat, 1–4 mm wide. |
sheaths closed 25–75% of their length, bases of basal sheaths glabrous; collars smooth or scabrous, glabrous, ligules of cauline leaves 1–3(6)mm; tips truncate to acute, ligules of sterile shoots 0.2– 0.5(2.5)mm; tips usually truncate; blades involute to flat, 0.2– 3.5 mm wide; all about equal or the upper ones slightly reduced in length; upper surface usually densely scabrous or hispidulous to softly puberulent, infrequently nearly smooth and glabrous; lower surface smooth or scabrous; uppermost blade 0.5–5(6)cm. |
Inflorescences | lax; open; sparse, 5–15 cm; branches spreading to reflexed; capillary; (2)3– 8 cm, 1–3(5) per node, usually moderately scabrous, with (3)4– 15 spikelets. |
usually erect, tightly or loosely contracted, narrowly lanceoloid to ovoid, 2–10(12) cm; spikelets 10–100; branches erect or steeply ascending, 0.5–4(5)cm long, 1–3(5) per node, with 1–15 spikelets. |
Spikelets | lanceolate or narrowly lanceolate, 4–8 mm, green, or partly purple to dark purple; florets 2–5. |
broadly lanceolate to narrowly ovate; to 3 times as long as wide; (3)4–10 mm; florets 2–6; rachilla internodes 0.5–1.2 mm long. |
Glumes | tapered from the base or lanceolate; thin; keels usually scabrous; lower glumes 1-veined; upper glumes distinctly shorter than to nearly equaling lowest lemma. |
lanceolate; lower glumes 3-veined, distinctly shorter than the lowest lemma. |
Calluses | with sparse cobwebby hairs. |
glabrous or with short; sparse, sometimes diffuse cobwebby hairs less than 25% of the lemma length. |
Lemmas | lanceolate, 3–4 mm, often partly purple, distinctly keeled; thin; smooth, or sparsely scabrous near the tip; keels softly puberulent to long-villous on 25–67% the length; marginal veins softly puberulent to long-villous; hairs frequently sparse; lateral veins and area between veins glabrous; margins infolded; tips sharply acute to acuminate, usually bronze-colored. |
lanceolate to broadly lanceolate; (3)4–7 mm, distinctly keeled, membranous; smooth or sparsely to densely scabrous, glabrous throughout, or keels and/or marginal veins softly puberulent near the base; tips acute. |
Anthers | 0.2–1.1 mm. |
vestigial and 0.1–0.2 mm, aborted late in development, or well developed and 2–3.5 mm. |
2n | =42. |
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Poa leptocoma |
Poa cusickii |
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Distribution | ||
Discussion | Montane to alpine streamsides, lakeshores, and wet meadows. 1100–2800m. BR, BW, Casc, ECas, Sisk. CA, ID, NV, WA; western Canada and US; Asia. Native. Poa leptocoma is a loosely cespitose grass with short anthers and somewhat open panicles. It is most similar to P. reflexa, a plant of drier habitats that has less scabrous panicle branches, longer anthers, and sparsely hairy lateral lemma veins, at least on one side of the lemma. |
4 subspecies. Poa cusickii is a common upland bluegrass with a dense inflorescence. It is usually densely cespitose, though some plants may have short rhizomes. Similar P. fendleriana has reduced uppermost flag blades, and lemmas with silky hairs on the keels and marginal veins. Poa leibergii has narrower leaves and usually longer ligules. Poa wheeleri can be misidentified as P. cusickii if the specimen is collected without its distinctive scabrous leaf sheaths. Poa pringlei, restricted to southwestern Oregon near the California border, has longer ligules, sheaths closed to about a third their length, and glabrous (to scabrous) lemmas. It is dioecious, whereas P. cusickii plants are bisexual or entirely pistillate. |
Source | Flora of Oregon, volume 1, page 459 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Flora of Oregon, volume 1, page 455 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Poa leptocoma ssp. leptocoma, Poa leptocoma var. leptocoma, Poa vaseyochloa | |
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