Poa saltuensis |
Poa infirma |
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old-pasture blue grass |
diploid annual bluegrass, weak blue grass |
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Habit | Plants perennial; not rhizomatous, not stoloniferous, loosely tufted. | Plants annual; neither rhizomatous nor stoloniferous, densely tufted. | ||||
Culms | 20-95 cm tall, 0.8-1.5 mm thick. |
2-15 cm, prostrate to erect, slender; nodes terete, usually 1 exserted. |
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Sheaths | closed for 1/3-2/3 their length; ligules 0.2-3(4) mm, smooth or sparsely scabrous, truncate to obtuse; blades 1-3.6 (6) mm wide, flat, thin, lax, veins prominent. |
closed for about 1/3 their length, terete or weakly compressed, smooth; ligules 0.5-3 mm, smooth, glabrous, decurrent, obtuse to truncate; blades 1-3(4) mm wide, flat, thin, soft, smooth, margins usually slightly scabrous, apices broadly prow-shaped. |
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Basal branching | mainly pseudointravaginal. |
intravaginal, sterile shoots common, similar to the culms. |
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Panicles | 4-20(24) cm long, less than 1/4 the plant height, lax; nodes with 1-3 branches; branches ascending to spreading, lax, angled, angles prominent, scabrous. |
1-6 cm, lengths 1.5-3 times widths, erect; nodes with 1-2(5) branches; branches ascending, straight, terete, smooth, with crowded spikelets. |
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Spikelets | 3-5.6 mm, laterally compressed; florets 2-5; rachilla internodes glabrous, usually shorter than 1 mm. |
3-5 mm, laterally compressed; florets 2-6; rachilla internodes smooth, glabrous, usually exposed in side view, distal internodes 1/2 - 3/4 the length of tbe distal lemma. |
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Glumes | 2/3 – 3/4 as long as the adjacent lemmas, distinctly keeled; lower glumes 1(3)-veined; upper glumes shorter than or subequal to the lowest lemmas; calluses webbed; lemmas 2.4-4 mm, lanceolate to broadly lanceolate, distinctly keeled, usually glabrous, bases of marginal veins rarely sparsely softly puberulent, lateral veins prominent, intercostal regions smooth, minutely bumpy, apices obtuse to sharply acute or acuminate; palea keels scabrous; anthers 0.4-1.5 mm. |
smooth, distinctly keeled, keels smooth; lower glumes 1-veined; upper glumes shorter than or subequal to the lowest lemmas; calluses glabrous; lemmas 2-2.5 mm, lanceolate, distinctly keeled, smooth throughout, the keels, marginal and lateral veins crisply puberulent to long-villous, lateral veins prominent, intercostal regions glabrous, margins smooth, glabrous, apices obtuse to acute; palea keels smooth, short- to long-villous; anthers 0.1-0.6 mm, more or less spherical to short-elliptical prior to dehiscence, those of the upper 1-2 florets commonly vestigial. |
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2n | = 14. |
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Poa saltuensis |
Poa infirma |
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Distribution |
CT; IA; IL; IN; KY; MA; MD; ME; MI; MN; NC; NH; NJ; NY; OH; PA; RI; TN; VA; VT; WI; WV; LB; NB; NS; ON; PE; QC
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CA; OR; SC; BC |
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Discussion | Poa saltuensis grows in woodlands of the north-central and northeastern United States and adjacent Canada, extending south to Tennessee. The two subspecies are sometimes treated as species. The variation between the two overlaps and is correlated to some extent with ecology and geography. Poa marcida (p. 512), a western species once included in P. saltuensis, differs in having closed sheaths and attenuate lemmas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa infirma was introduced from Europe to the Americas, and was first described from Colombia. It is sporadically established along the Pacific coast and in the central valleys of California, and has been collected in Charleston, South Carolina. It is rare elsewhere in the Flora region. Poa annua often resembles P. infirma (see previous), which is thought to be one of its parents, but P. annua is tetraploid and has anthers 0.6-1.1 mm long. Both species are gynomonoecious. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 24, p. 510. | FNA vol. 24, p. 519. | ||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Sylvestres | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Micrantherae | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. saltuensis var. microlepis, P. languida | |||||
Name authority | Fernald & Wiegand | Kunth | ||||
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