Ptilagrostis porteri

(Rydb.) W.A. Weber
Common names: Porter's ptilagrostis Rocky-mountain ptilagrostis
Treatment appears in FNA Volume 24. Treatment on page 144.

Culms 23-50 cm tall, 0.6-1.2 mm thick. Lower ligules 0.7-1.5 mm; upper ligules to 2.5 mm; blades filiform, 0.3-0.6 mm in diameter. Panicles 7.5-12 cm, open or loosely contracted; branches spreading. Glumes 4.5-6 mm; florets 2.5-4 mm; calluses 0.1-0.8 mm; lemmas with 0.2-0.8 mm lobes; awns 5-25 mm, hairy, hairs on the lowest segment 1-2 mm; anthers 1.2-3 mm, glabrous. 2n = unknown.

Discussion

Ptilagrostis porteri grows on hummocks of poorly drained wetlands, at 2700-3600 m, in central Colorado. It is often associated with Salix spp. and Deschampsia cespitosa. There are 29 known populations.

The proportion of plants having closed and open panicles varies among the populations; in some populations all or almost all plants have open panicles, in others all or almost all plants have closed panicles (Johnston 2006). Barkworth (1983) treated P. porteri as a subspecies of P. mongolica (Turcz. ex Trin.) Griseb. because of their morphological similarity. They differ ecologically and geographically, P. mongolica sensu stricto growing in rocky alpine habitats of central Asia.

Selected References

None.

Lower Taxa

None.

"decumbent" is not a number."prolonged" is not a number.

... more about "Ptilagrostis porteri"
membranous +  and scarious +
penicillate +
0.12 cm1.2 mm <br />0.0012 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
awned +, bifid +, bilobed +  and entire +
Rounded (?) +, Lobed (?) +  and Acute (?) +
Mary E. Barkworth +
(Rydb.) W.A. Weber +
twisted +  and not branched +
1 (?) +  and 3 (?) +
subterminal +  and eccentric +
0.5 cm5 mm <br />0.005 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
not evident +
filiform +
straight +  and flexuous +
hirtellous +  and glabrous +
capillary +
well-developed +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
Porter's ptilagrostis +  and Rocky-mountain ptilagrostis +
not branching +
perennial +  and annual +
23 cm230 mm <br />0.23 m <br /> (50 cm500 mm <br />0.5 m <br />) +
not woody +
0.06 cm0.6 mm <br />6.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
Colo. +  and N.Mex. +
0 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
2.5mm +  and 4mm +
purplish +  and hyaline +
1-10-veined +
subtending +
narrowly lanceolate +  and ovate +
subequal +
0.45 cm4.5 mm <br />0.0045 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
membranous +
not keeled +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
solid +  and hollow +
basally concentrated +  and evenly distributed +
ovate +, rectangular +  and lanceolate +
membranous +
rounded +  and acute +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
membranous +
membranous +
inconspicuous +
lanceolate +
not overlapping +
2 +  and 1 +
well-developed +
slightly longer +
reduced +
7.5 cm75 mm <br />0.075 m <br /> (12 cm120 mm <br />0.12 m <br />) +
dry +  and fleshy +
not prolonged +
smooth to somewhat +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
0.34 cm3.4 mm <br />0.0034 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Ptilagrostis porteri +
Ptilagrostis +
species +
membranous +
inconspicuous +
plant +  and cespitose +
aquatic +  and terrestrial +
12 +, 11 +, 10 +, 8 +  and 7 +