Poa arctica subsp. caespitans

Simmons ex Nannf.
Synonyms: Poa arctica var. vivipara Hook.
Treatment appears in FNA Volume 24. Treatment on page 532.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Plants densely to moderately densely tufted, rhizomatous, rhizomes very short, poorly developed. Sheaths closed for (1/5) 1/3 their length, terete; ligules 2-4 mm, obtuse to acute; blades 1-2.5 mm wide, flat or folded, moderately thick. Panicles lax to erect, open; branches ascending or widely spreading, sinuous and flexuous to fairly straight, smooth or the angles moderately or densely scabrous, proximal branches 1/4-1/2 the panicle length. Spikelets 4.5-8 mm, laterally compressed, infrequently bulbiferous; rachilla internodes usually glabrous, infrequently sparsely softly puberulent; calluses webbed; lemmas 3-6 mm; palea keels glabrous or long-villous; anthers usually aborted late in development, infrequently fully developed. 2n = 56, ca. 66, ca. 80.

Discussion

Poa arctica subsp. caespitans grows in moist tundra of the high arctic, or infrequently in the low arctic of northeastern Canada and Greenland. It also grows in Norway and in the Russian high arctic; it is rare in both regions.

Many plants included here tend towards Poa glauca (p. 576, e.g., scabrous branches, and intermediate leaf and panicle forms), while others are distinguished from other P. arctica subspecies only by their more tufted habit and sterile anthers. As interpreted here, subsp. caespitans includes P. trichopoda Lange [= P. tolmatchewii Roshev.].

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number.

80 +, 66 +  and 56 +
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 +
Simmons ex Nannf. +
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 +
thick;1mm;2.5mm +
flexuous +  and fairly straight +
spreading;ascending +
hispidulous +, glabrous +, smooth or +  and sparsely densely scabrous +
compressed +  and terete +
reduced +  and subequal +
unbranched +  and hollow +
ascending +  and erect +
compressed +  and terete +
slender +  and stout +
7.5 cm75 mm <br />0.075 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 +
3 +  and 6 +
compressed +
reduced +
1-3(5)-veined +
shorter or longer +
subtending +
lanceolate +  and broadly lanceolate distinctly or weakly keeled +
subequal +  and unequal +
distributed +
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 +
glabrous +, puberulent +, short-villous +  and softly puberulent +
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 /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
erose +  and entire +
white +  and milky white or hyaline +
obtuse +  and acute +
0.2 cm2 mm <br />0.002 m <br /> (0.4 cm4 mm <br />0.004 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 +
3.5 cm35 mm <br />0.035 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 +
compressed +
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 arctica var. vivipara +
Poa arctica subsp. caespitans +
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 +