Poa annua |
Poa saltuensis |
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annual blue grass |
old-pasture blue grass |
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Habit | Plants usually annual, rarely surviving for a second season; not rhizomatous, sometimes stoloniferous, densely tufted. | Plants perennial; not rhizomatous, not stoloniferous, loosely tufted. | ||||
Culms | 2-20(45) cm, prostrate to erect, slender; nodes terete, usually 1 exserted. |
20-95 cm tall, 0.8-1.5 mm thick. |
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Sheaths | closed for about 1/3 their length, terete or weakly compressed, smooth; ligules 0.5-3(5) mm, smooth, glabrous, decurrent, obtuse to truncate; blades 1-10 cm long, 1-3(6) mm wide, flat or weakly folded, thin, soft, smooth, margins usually slightly scabrous, apices broadly prow-shaped. |
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. |
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Basal branching | intravaginal, innovations common, similar to the culms. |
mainly pseudointravaginal. |
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Panicles | 1-7(10) cm, lengths 1.2-1.6 times widths, erect; nodes with 1-2(3) branches; branches ascending to spreading or reflexed, straight, terete, smooth, with crowded or loosely arranged spikelets. |
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. |
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Spikelets | 3-5 mm, laterally compressed; florets 2-6; rachilla internodes smooth, glabrous, concealed or exposed, distal internodes less than 1/2(3/4) the length of the distal lemma. |
3-5.6 mm, laterally compressed; florets 2-5; rachilla internodes glabrous, usually shorter than 1 mm. |
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Glumes | smooth, distinctly keeled, keels smooth; lower glumes 1-veined; upper glumes shorter than or subequal to the lowest lemma; calluses glabrous; lemmas 2.5-4 mm, lanceolate, distinctly keeled, smooth throughout, the keels, marginal veins, and, usually, lateral veins crisply puberulent to long-villous, rarely glabrous throughout, lateral veins prominent, intercostal regions glabrous, margins smooth, glabrous, apices obtuse to acute; palea keels smooth, usually short- to long-villous, rarely glabrous; anthers 0.6-1.1 mm, oblong prior to dehiscence, those of the upper 1-2 florets usually vestigial. |
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. |
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2n | = 28. |
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Poa annua |
Poa saltuensis |
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Distribution |
AK; AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; HI; PR; AB; BC; MB; NB; NL; NS; NT; ON; PE; QC; SK; YT; Greenland
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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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Discussion | Poa annua is one of the world's most widespread weeds. It thrives in anthropomorphic habitats outside of the arctic. A native of Eurasia, it is now well established throughout most of the Flora region. Poa annua is a gynomonoecious tetraploid (possibly rarely polyhaploid), and is thought to have arisen from hybridization between P. infirma (see next) and P. supina (p. 521) (Tutin 1952). It is similar to P. infirma, differing in having larger anthers. It differs from P. chapmaniana (p. 534) in having glabrous calluses and three larger anthers, rather than one. Forms with glabrous lemmas occur sporadically within populations. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
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Key |
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Source | FNA vol. 24, p. 519. | FNA vol. 24, p. 510. | ||||
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Micrantherae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Sylvestres | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | P. annua var. reptans, P. annua var. aquatica | P. saltuensis var. microlepis, P. languida | ||||
Name authority | L. | Fernald & Wiegand | ||||
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