Poa tenerrima

Scribn.
Common names: Delicate bluegrass
Endemic
Treatment appears in FNA Volume 24. Treatment on page 588.
Please click on the illustration for a higher resolution version.
Illustrator: Sandy Long

Copyright: Utah State University

Plants perennial; densely tufted, basal leaf tufts 2-8 (13) cm, small, narrowly based, not stoloniferous, not rhizomatous. Basal branching intravaginal. Culms 15-50 cm tall, slender, 0.8-0.9 mm thick; nodes terete, 0-1 exserted. Sheaths closed for 76-74 their length, terete, scabrous, glabrous, bases of basal sheaths glabrous, distal sheath lengths 2.3-7.7 times blade lengths; collars sparsely scabrous, glabrous; ligules 0.5-1.5 (2.5) mm, scabrous, apices usually truncate to obtuse, sometimes acute, ligules of innovations to 0.5 mm; innovation blades filiform; cauline blades gradually reduced in length upwards, 0.4-1.5 mm wide, mostly folded, thin, soft, soon withering, scabrous, apices narrowly prow-shaped. Panicles 5-15 cm, 1.3-2.2 times the branch lengths, erect, broadly rhomboidal to pyramidal, open, purple, sparse, proximal internodes 1.5-4.2 cm; nodes with 1-2 (5) branches; branches 3-8.5 cm, widely spreading, capillary, straight, terete to weakly angled, moderately to mostly densely scabrous, with 3-9 spikelets in the distal 73. Spikelets 5-8 mm, lengths (3.8) 4-5 times widths, usually narrowly lanceolate to lanceolate, subterete to weakly laterally compressed, drab, usually strongly anthocyanic; florets 3-5; rachilla internodes 1-1.5+ mm, terete or slightly dorsally compressed, muriculate or scabrous. Glumes lanceolate, distinctly shorter than the adjacent lemmas, scabrous distally, keels indistinct, scabrous, obtuse to acute; lower glumes 3-veined; calluses glabrous or with a crown of hairs, hairs to 0.3 mm; lemmas 3-4.2 mm, lanceolate, weakly keeled, keels, veins, and proximal 2/3 of the intercostal regions puberulent, lateral-veins obscure, margins strongly inrolled below, broadly scarious above, glabrous, apices obtuse to acute; palea keels scabrous, sometimes hairy at midlength; anthers 1.6-2.1 mm. 2n = 42.

Discussion

Poa tenerrima is a rare species, endemic to serpentine barrens along the western base of the Sierra Nevada. It differs from P. secunda subsp. secunda (see previous) in combining consistently wide, open panicles, very scabrous branches, short-truncate ligules, and very fine foliage. A series of small, delicate, open-panicled plants from the California Coast Ranges, formerly included in P. tenerrima by Soreng (1993), differ in having smooth branches and longer ligules, and are better referred to P. secunda subsp. secunda. No intergradation is evident where the two taxa grow together. Plants from the Columbia River Gorge in Oregon, including the type of P. multnomae Piper, approach P. tenerrima, but are presumed to be derived from hybridization between P. nervosa (p. 545) and P. secunda (p. 586).

Selected References

None.

Lower Taxa

None.

"thin" is not a number.No values specified."decumbent" is not a number.

... more about "Poa tenerrima"
membranous +  and scarious +
puberulent +, hispidulous +, hairy +  and glabrous +
5 cm50 mm <br />0.05 m <br /> (?) +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.21 cm2.1 mm <br />0.0021 m <br />) +
scarious-hyaline +
obtuse +  and acute +
Robert J. Soreng +
Scribn. +
1 (?) +  and 3 (?) +
straight +
basal +  and terminal +
keeled +  and rounded +
strigose +  and glabrous +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
persisting +
not evident +
involute +, folded +  and flat +
hispidulous +, glabrous +, smooth or +  and sparsely densely scabrous +
terete +  and weakly angled +
3 cm30 mm <br />0.03 m <br /> (8.5 cm85 mm <br />0.085 m <br />) +
with a crown +  and glabrous +
compressed +  and terete +
Delicate bluegrass +
unbranched +  and hollow +
15 cm150 mm <br />0.15 m <br /> (50 cm500 mm <br />0.5 m <br />) +
ascending +  and erect +
compressed +, terete +  and capillary +
slender +
10 cm100 mm <br />0.1 m <br /> (120 cm1,200 mm <br />1.2 m <br />) +
not woody +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.09 cm0.9 mm <br />9.0e-4 m <br />) +
1/4 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
3 +  and 5 +
compressed +
reduced +
bulb-forming +  and normal +
1-3(5)-veined +
shorter or longer +
subtending +
lanceolate +
unequal +
distributed +
uncinate +
0 cm0 mm <br />0 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
0 +  and 1/6 +
Oval (?) +  and Round (?) +
milky white +  and slightly greenish +
indistinct +
obtuse +  and acute +
5(7-11)-veined +
keeled +  and lanceolate +
subequal +
0.3 cm3 mm <br />0.003 m <br /> (0.42 cm4.2 mm <br />0.0042 m <br />) +
membranous +
erose +  and entire +
white +  and milky white or hyaline +
ciliolate +  and smooth +
lacerate +, truncate +  and acuminate +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 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 +
30 cm300 mm <br />0.3 m <br /> (?) +
1.3-2.2 times the branch lengths +
broadly rhomboidal +  and pyramidal +
5 cm50 mm <br />0.05 m <br /> (15 cm150 mm <br />0.15 m <br />) +
dry +  and fleshy +
1.5 cm15 mm <br />0.015 m <br /> (4.2 cm42 mm <br />0.042 m <br />) +
pubescent +, glabrous +, scabrous +  and smooth +
usually narrowly lanceolate +  and lanceolate subterete +
0.5 cm5 mm <br />0.005 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
1 +  and 3 +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Poa tenerrima +
Poa subsect. Secundae +
species +
membranous +
parallel +  and converging +
stoloniferous +  and rhizomatous +
aquatic +  and terrestrial +