Poa arida |
Poa secunda |
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secund bluegrass |
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Habit | Plants perennial, (10)15–120 cm tall; densely cespitose; basal leaf tufts (excluding culms) 2–20+ cm tall, glaucous or not. | |
Culms | slender to stout; nodes terete, 0–2 exserted. |
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Basal branching | intra- and extravaginal. |
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Leaves | sheaths closed to 25% of their length, bases of basal sheaths glabrous; collars smooth or scabrous, glabrous; ligules 0.5–6(10)mm; blades flat, folded, or involute, 0.4–3(5) mm wide, green to strongly glaucous; thin; soft and soon withering, or thick; firm and persisting; smooth, or scabrous mainly over the veins; blades gradually reduced distally or the middle blades longest; uppermost blades 0.8–10(17)cm. |
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Inflorescences | erect or somewhat lax, narrowly lanceoloid to ovoid, usually contracted; more or less open in flower, infrequently remaining open at maturity, usually moderately congested, 2–25(30) cm; spikelets 10–100+; branches usually erect or ascending, infrequently spreading at maturity; (0.5)1–8(10) cm, 1–3 per node, with (1)2–20(60+) spikelets in distal 50–67%. |
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Spikelets | usually narrowly lanceolate; more or less terete to slightly laterally compressed; (3.8)4–5 times as long as wide; (4)5–10 mm; florets (2)3–5(10); rachilla internodes usually 1–2 mm long; smooth to scabrous. |
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Glumes | broadly lanceolate; keels indistinct; lower glumes 3-veined. |
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Calluses | glabrous, or with a line of crisp or slightly sinuous hairs 0.1–0.5(2) mm long around the base. |
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Lemmas | lanceolate to narrowly lanceolate or slightly oblanceolate, 3.5–6 mm, usually weakly keeled, glabrous throughout or keels and marginal veins softly puberulent to short-villous; area between veins smooth or scabrous, glabrous; short-villous, crisply puberulent, or loosely softly puberulent over the basal 67%; hairs usually 0.1–0.5 mm long; margins strongly inrolled below, broadly scarious above, glabrous; tips obtuse to broadly acute; blunt or pointed. |
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Anthers | 1.5–3 mm. |
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Poa arida |
Poa secunda |
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Distribution | ||
Discussion | 2 subspecies. Poa secunda is a common, highly variable, densely cespitose grass mainly of uplands. The spikelets are terete to slightly compressed, and the lemmas are more or less rounded over the back and usually hairy to scabrous throughout. Poa stenantha can be very similar, but its lemmas are a bit more strongly keeled and have hairs only on the veins. Callus hairs, if present, are 0.2–2 mm long. Hybrids between P. secunda and P. pratensis (P. × limosa) occur in moist, alkaline meadows in southeastern Oregon. They resemble P. secunda but are more or less rhizomatous and may have more strongly keeled lemmas. Hybrids with P. nervosa, called P. × multnomae, occur in the Columbia Gorge. They have more open panicles and generally grow in moister habitats than P. secunda. Puccinellia lemmonii and Poa secunda are superficially similar, but Puccinellia lemmonii has lower glumes that are less than 50% as long as the lowest lemma, and it grows in more strongly alkaline meadows and flats that are generally wet in spring. Poa secunda is a highly variable taxon. Its combination of asexual and sexual seed production produces multiple widespread, morphologically consistent forms that are sympatric. Many of these variants have been treated as species. However, intermediates can be found between all of them. Here we gather these forms into two categories treated as subspecies. |
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Source | Flora of Oregon, volume 1, page 465 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
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Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Poa canbyi | |
Web links |
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