Poa chambersii

Soreng
Common names: Chambers' bluegrass
Treatment appears in FNA Volume 24. Treatment on page 548.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Plants perennial; loosely tufted or with solitary shoots, short-rhizomatous. Basal branching all or mainly extravaginal. Culms 10-50 cm, erect or the bases decumbent, terete or weakly compressed; nodes terete, 0-1 exserted. Sheaths closed for 1/3 – 7/8 their length, terete to slightly compressed, smooth, glabrous, bases of basal sheaths glabrous, distal sheath lengths (1.15) 1.5-4.6 (6.6) times blade lengths; collars smooth, glabrous; ligules 0.5-2 (2.5) mm, smooth, truncate to obtuse; innovation blades similar to the cauline blades; cauline blades gradually reduced in length distally, 2-5 mm wide, flat or folded, smooth or the adaxial surfaces sparsely scabrous, primarily over the veins, apices broadly prow-shaped, flag leaf-blades 0.7-6 cm. Panicles 2-9 cm, erect, lanceoloid to ovoid, tightly to loosely contracted, with 15-35 spikelets, proximal internodes shorter than 2 cm; nodes with 1-2 branches; branches 0.9-3.2 cm, erect to ascending or slightly spreading, terete, smooth or sparsely scabrous, with 1-4 spikelets. Spikelets 6-12 mm, lengths to 3 times widths, laterally compressed, not sexually dimorphic; florets 2-7; rachilla internodes 0.8-1.5 mm, smooth or sparsely scabrous, glabrous. Glumes 3/5- 4/5 as long as the adjacent lemmas, distinctly keeled; lower glumes 3-veined; calluses of at least some proximal florets sparsely webbed, with 1-2 mm hairs, others glabrous, rarely all glabrous; lemmas 5-7 mm, lanceolate, 5-7-veined, distinctly keeled, smooth or sparsely finely scabrous, glabrous throughout or the keels and marginal veins sparsely softly puberulent over the proximal 1/4, lateral-veins moderately prominent, intercostal regions glabrous, margins glabrous, apices acute; palea keels sparsely scabrous, intercostal regions glabrous; anthers vestigial (0.1-0.2 mm), aborted late in development, or 1.8-3.7 mm. 2n = unknown.

Discussion

Poa chambersii is known only from upland forest openings in the Cascades of western Oregon, where it is dioecious, and from high elevations on Steens Mountain in southeastern Oregon, where it is gynodioecious. It resembles P. rhizomata (see previous), but has more closed sheaths, shorter ligules, less pubescent or glabrous lemmas, and lacks a well-developed web. It approaches P. cusickii subsp. purpurascens (p. 562), but is rhizomatous and sexually reproducing. It differs from P. wheeleri (p. 546) in having glabrous sheaths and flat or folded, glabrous innovation blades.

Selected References

None.

Lower Taxa

None.

"thin" is not a number."reduced" is not a number."decumbent" is not a number.

... more about "Poa chambersii"
membranous +  and scarious +
hispidulous +, glabrous +, scabrous +  and smooth +
5 cm50 mm <br />0.05 m <br /> (?) +
0.18 cm1.8 mm <br />0.0018 m <br /> (0.37 cm3.7 mm <br />0.0037 m <br />) +
scarious-hyaline +
acute +  and prow--shaped +
Robert J. Soreng +
Soreng +
1 (?) +  and 3 (?) +
straight +
basal +  and terminal +
keeled +  and rounded +
strigose +  and glabrous +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
compressed +  and terete +
swelling +
not evident +
involute +, folded +  and flat +
erect;ascending or slightly spreading +
hispidulous +, glabrous +, smooth or +  and sparsely densely scabrous +
0.9 cm9 mm <br />0.009 m <br /> (3.2 cm32 mm <br />0.032 m <br />) +
webbed +  and glabrous +
compressed +  and terete +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Chambers' bluegrass +
unbranched +  and hollow +
terete or +  and weakly strongly compressed +
10 cm100 mm <br />0.1 m <br /> (50 cm500 mm <br />0.5 m <br />) +
not woody +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
2 +  and 7 +
compressed +
reduced +
1-3(5)-veined +
shorter or longer +
subtending +
3/5 +  and 4/5 +
unequal +
distributed +
uncinate +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
0 +  and 1/6 +
Oval (?) +  and Round (?) +
hispidulous +, glabrous +, scabrous +  and smooth +
milky white +  and slightly greenish +
puberulent +
glabrous +, scabrous +  and smooth +
keeled +  and lanceolate +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
membranous +
erose +  and entire +
white +  and milky white or hyaline +
puberulent +, glabrous +, scabrous +  and smooth +
truncate +  and obtuse +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
membranous +
inconspicuous +
lobed +  and lanceolate +
milky white +  and slightly greenish +
concealed +  and prominent +
0 +  and 1 +
2 +  and 1 +
well-developed +
2-keeled +
subequal +
lanceoloid +  and ovoid +
2 cm20 mm <br />0.02 m <br /> (9 cm90 mm <br />0.09 m <br />) +
dry +  and fleshy +
2 cm20 mm <br />0.02 m <br /> (?) +
glabrous +, scabrous +  and smooth +
terete +  and slightly compressed +
short-rhizomatous +
not bulbiferous +
compressed +
0.6 cm6 mm <br />0.006 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Poa chambersii +
Poa subsect. Poa +
species +
membranous +
parallel +  and converging +
with solitary shoots +  and tufted +
aquatic +  and terrestrial +