Poa macrantha |
Poa annua |
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seashore bluegrass |
annual bluegrass |
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Habit | Plants perennial, dioecious, (7)15–60 cm tall; loosely cespitose, rhizomatous, and stoloniferous, rhizomes and stolons to 400 cm long. | Plants annual, rarely biennial, 2–20(45)cm tall; cespitose. |
Culms | stout, 1.5–2 mm thick; nodes terete, 0(1) exserted. |
nodes terete or weakly compressed. |
Basal branching | mainly intravaginal; some extravaginal. |
intravaginal. |
Leaves | sheaths closed about 50% of their length, bases of basal sheaths glabrous; collars smooth, glabrous; ligules 1–5 mm; blades moderately to densely scabrous or minutely hairy on and between veins, blades of tillers to 30 cm; cauline blades involute; somewhat arcuate, 2–4 mm wide; uppermost blades 1–10 cm. |
sheaths closed about 33% of their length; ligules 0.5–3(5) mm; blades flat or weakly folded, 1–10 cm × 1–3(6)mm; smooth. |
Inflorescences | erect; ovoid to lanceolate, contracted, often interrupted, 3–15 cm; spikelets 15–80; branches 1-2; erect, 1–6 cm; stiff, with 3–17 spikelets. |
1–7(10)cm; branches ascending to spreading or reflexed. |
Spikelets | 9–17 mm; to 3 times as long as wide; florets 3–6(10). |
3–5 mm long; florets 2–6; rachilla internodes smooth, glabrous; more or less concealed, occasionally exposed; distal rachilla internode less than 50(75)% of the length of distal lemma. |
Glumes | broadly lanceolate, subequal to adjacent florets; keels sparsely scabrous near tips; lower glumes 3-veined; upper glumes usually more than 7 mm, 3–5-veined. |
lower glumes smooth, 1-veined. |
Calluses | usually with a line of crisp to sinuous hairs around the base of the lemma, sometimes glabrous or with diffuse; short; cobwebby hairs. |
glabrous. |
Lemmas | lanceolate; (6)7.5–11 mm, 5–7(11)-veined, distinctly keeled; keels and marginal veins, sometimes also intermediate veins; short-villous to softly puberulent; area between veins smooth to scabrous, glabrous or softly puberulent; tips acute. |
lanceolate, 2.5–4 mm, keeled; smooth; keels; marginal veins; and usually intermediate veins crisply puberulent to long-villous, rarely glabrous; area between veins glabrous; tips obtuse to acute. |
Anthers | vestigial and 0.1–0.2 mm, or (2)3–4(5)mm. |
0.6–1.1 mm, oblong. |
2n | =28. |
=28. |
Poa macrantha |
Poa annua |
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Distribution | ||
Discussion | Coastal sand dunes. 0–100m. Est. CA, WA; north to AK. Native. |
Disturbed areas, parking lots, lawns, shores. 0–1700m. BR, BW, Casc, Col, CR, Est, Lava, Sisk, WV. CA, ID, NV, WA; throughout southern Canada and US; worldwide. Exotic. Poa annua is a small but abundant annual with spreading inflorescence branches and oblong anthers. Poa infirma is very similar but has ascending inflorescence branches and shorter, nearly spherical anthers. Poa supina, supine bluegrass, has inflorescences similar to P. annua, but it is a stoloniferous perennial with longer anthers. It is planted on shady golf courses and lawns where it forms dense, spongy turf. It has not been found in the wild in Oregon but is expected to escape here. |
Source | Flora of Oregon, volume 1, page 460 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Flora of Oregon, volume 1, page 453 Rob Soreng, Barbara Wilson, Richard Brainerd, Nick Otting |
Sibling taxa | ||
Web links |
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