Poa annua |
Poa pseudoabbreviata |
|
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annual blue grass |
polar bluegrass, short-flower bluegrass, shortcoal bluegrass |
|
Habit | Plants usually annual, rarely surviving for a second season; not rhizomatous, sometimes stoloniferous, densely tufted. | Plants perennial; glaucous; densely tufted, delicate, not stoloniferous, not rhizomatous. |
Culms | 2-20(45) cm, prostrate to erect, slender; nodes terete, usually 1 exserted. |
4-20(30) cm, to 18 cm in bulbiferous plants, slender. |
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 1/10 – 1/6 their length, terete; ligules 1-4 mm, smooth; blades 0.5-1.5(2) mm wide, flat or folded, thin, soft, apices narrowly prow-shaped. |
Basal branching | intravaginal, innovations common, similar to the culms. |
all or mainly intravaginal. |
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. |
2-7 cm, 2-4 cm in bulbiferous plants, widths equal to lengths, erect, broadly rhomboidal to pyramidal, open, exserted from the sheaths, sparse; branches 1.5-5 cm, ascending to spreading, divaricate, slender, sulcate or angled, angles sparsely to moderately scabrous; pedicels often longer than the spikelets. |
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 mm, laterally compressed, rarely bulbiferous, usually strongly anthocyanic, glaucous or not; florets 2-4, rarely bulb-forming; rachilla internodes shorter than 1 mm, smooth to scabrous. |
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. |
distinctly keeled; lower glumes subequal to equaling the lowest lemmas, 3-veined, upper glumes frequently longer than the lowest lemmas; calluses glabrous; lemmas 2-3 mm, lanceolate, distinctly keeled, thin, keels and marginal veins crisply puberulent, rarely glabrous, intercostal regions glabrous, apices acute; paleas scabrous over the keels; anthers 0.2-0.7 mm. |
2n | = 28. |
= 14. |
Poa annua |
Poa pseudoabbreviata |
|
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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AK; BC; NT; YT |
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 pseudoabbreviata is a low arctic to subarctic and alpine species of Alaska, northwestern Canada, Siberia, and the Russian Far East. It grows mainly on frost scars, rocky slopes, and ridges, often on open ground. It is one of only three diploid species native to the Western Hemisphere. Poa pseudoabbreviata is easily distinguished from all other alpine and arctic species of Poa by its spreading, capillary branches, long pedicels, short stature, small spikelets, and glabrous calluses. Bulbiferous plants are known only from the Brooks Range, Alaska. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 24, p. 519. | FNA vol. 24, p. 580. |
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Micrantherae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Abbreviatae |
Sibling taxa | ||
Synonyms | P. annua var. reptans, P. annua var. aquatica | P. brachyanthera |
Name authority | L. | Roshev. |
Web links |
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