Poa cusickii |
Poa reflexa |
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Cusick's bluegrass |
nodding bluegrass |
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Habit | Plants perennial, gynodioecious, or all pistillate, 10–60(70)cm long, usually densely cespitose with short rhizomes. | Plants perennial, short-lived, 10–60 cm tall; densely cespitose. |
Culms | 0.5–1.8 mm thick; nodes terete, 0–2 exserted. |
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Basal branching | intravaginal or intra- and extravaginal. |
intraand extravaginal. |
Leaves | 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. |
sheaths closed 33–50% of their length; smooth; ligules 1.5–3.5 mm; blades flat, 1.5–4 mm wide. |
Inflorescences | 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. |
nodding; open, 4–15 cm; branches spreading to reflexed, flexuous; (2)3–7 cm, 1–2 per node; smooth to sparsely scabrous, with (3)6–18 spikelets. |
Spikelets | 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. |
lanceolate to broadly lanceolate, 4–6 mm, usually partly to wholly purplish; florets 3–5. |
Glumes | lanceolate; lower glumes 3-veined, distinctly shorter than the lowest lemma. |
narrowly to broadly lanceolate; keels smooth or nearly so; lower glumes 1-veined; upper glumes shorter than or subequal to lowest lemma. |
Calluses | glabrous or with short; sparse, sometimes diffuse cobwebby hairs less than 25% of the lemma length. |
with cobwebby hairs. |
Lemmas | 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. |
lanceolate, 2–3.5 mm, partly to mostly purple colored, distinctly keeled; keels short- to long-villous for over 67% of their length; marginal veins short- to long-villous; lateral veins usually sparsely softly puberulent at least on one side; area between veins smooth; tips acute, slightly bronze colored or not. |
Anthers | vestigial and 0.1–0.2 mm, aborted late in development, or well developed and 2–3.5 mm. |
0.6–1 mm. |
Poa cusickii |
Poa reflexa |
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Distribution | ||
Discussion | 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. |
Subalpine and alpine meadows, streamsides, talus slopes. 1000–2600 m. BW. ID, NV; northeast to MT, southeast to NM. Native. Poa reflexa is a rare subalpine bluegrass similar to P. leptocoma. Poa leptocoma grows in wetter habitats and has glabrous lateral lemma veins and scabrous panicle branches. |
Source | Flora of Oregon, volume 1, page 455 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Flora of Oregon, volume 1, page 464 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Sibling taxa | ||
Subordinate taxa | ||
Web links |
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