Poa arctica subsp. aperta

(Scribn. & Merr.) Soreng
Endemic
Synonyms: Poa aperta
Treatment appears in FNA Volume 24. Treatment on page 530.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Plants pale green, often glaucous; usually densely tufted, rhizomes usually short, usually well developed. Culms 20-60 cm, several together, wiry, bases decumbent. Sheaths closed for (1/6) 1/5 – 1/3 their length; ligules 3-7 mm, sparsely to moderately scabrous, acute; blades 1.5-2.5 mm wide, flat, folded, or somewhat involute. Panicles 4-15 cm, erect, loosely contracted or open, with 1-3 branches per node; branches ascending or widely spreading, fairly stout, fairly straight, smooth to very sparsely scabrous, proximal branches 1/4-1/2 the panicle length. Spikelets narrowly lanceolate to lanceolate, not bulbiferous; florets 2-3 (4), normal; rachilla internodes usually glabrous, infrequently sparsely softly puberulent; calluses glabrous or webbed, hairs to 1/4 the lemma length; lemmas 3-4.5 (6) mm; palea keels usually softly puberulent to long-villous at midlength, infrequently glabrous, intercostal regions usually softly puberulent; anthers aborted late in development or fully developed. 2n = 98+1.

Discussion

Poa arctica subsp. aperta is restricted to subalpine and low alpine habitats on the Wasatch Escarpment and high mountains of the Colorado Plateau in southern Utah, and the Rocky Mountains of southern Colorado and northern New Mexico. Many reports of P. arida (p. 599) growing west of the Rocky Mountains are based on misidentification of this subspecies. Poa arctica subsp. aperta may reflect introgression of genes from P. secunda (p. 586) into P. arctica. It has softer leaves, and is more densely hairy between the lemma veins and the palea keels, than subsp. arctica. It can be distinguished from subsp. grayana by its more wiry culms, and less contracted panicles with straighter branches.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number.

... more about "Poa arctica subsp. aperta"
membranous +  and scarious +
hairy +, scabrous +  and smooth +
5 cm50 mm <br />0.05 m <br /> (?) +
0.14 cm1.4 mm <br />0.0014 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
scarious-hyaline +
Robert J. Soreng +
(Scribn. & Merr.) Soreng +
1 (?) +  and 3 (?) +
straight +
basal +  and terminal +
keeled +  and rounded +
strigose +  and glabrous +
not branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
folded +  and flat +
1.5mm;2.5mm +
spreading;ascending +
hispidulous +, glabrous +, smooth or +  and sparsely densely scabrous +
scabrous +  and smooth to very +
webbed +  and glabrous +
compressed +  and terete +
reduced +  and subequal +
ascending +  and erect +
compressed +  and terete +
slender +  and stout +
20 cm200 mm <br />0.2 m <br /> (60 cm600 mm <br />0.6 m <br />) +
not woody +
Mont. +, Wyo. +, Colo. +, N.Mex. +, Wash. +, Utah +, Alaska +, Alta. +, B.C. +, Greenland +, Man. +, Nfld. and Labr. +, N.W.T. +, Nunavut +, Ont. +, Que. +, Sask. +, Yukon +, Idaho +  and Nev. +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
2 +  and 3 +
compressed +
reduced +
1-3(5)-veined +
shorter or longer +
subtending +
lanceolate +  and broadly lanceolate distinctly or weakly keeled +
subequal +  and unequal +
distributed +
0 +  and 1/4 +
uncinate +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
0 +  and 1/6 +
Oval (?) +  and Round (?) +
milky white +  and slightly greenish +
puberulent +  and glabrous +
prominent +  and pronounced +
5(7-11)-veined +
hairy +, glabrous +  and chartaceous +
keeled +, lanceolate +  and broadly lanceolate +
0.3 cm3 mm <br />0.003 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
membranous +
erose +  and entire +
white +  and milky white or hyaline +
0.3 cm3 mm <br />0.003 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
membranous +
inconspicuous +
lobed +  and lanceolate +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
concealed +  and prominent +
0 +  and 5 +
2 +  and 1 +
well-developed +
2-keeled +
subequal +
2 cm20 mm <br />0.02 m <br /> (?) +
ovoid +  and broadly pyramidal +
4 cm40 mm <br />0.04 m <br /> (15 cm150 mm <br />0.15 m <br />) +
dry +  and fleshy +
1.5 cm15 mm <br />0.015 m <br /> (?) +
puberulent +  and glabrous +
not bulbiferous +
narrowly lanceolate +  and lanceolate +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Poa aperta +
Poa arctica subsp. aperta +
Poa arctica +
subspecies +
membranous +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
parallel +  and converging +
aquatic +  and terrestrial +