Poa lettermanii |
Poa chaixii |
|
---|---|---|
Letterman bluegrass, Letterman's blue grass |
broadleaf bluegrass, Chaix's bluegrass |
|
Habit | Plants perennial; not glaucous; densely tufted, not stoloniferous, not rhizomatous. | Plants perennial; densely tufted, not stoloniferous, not rhizomatous. |
Culms | 1-12 cm, slender. |
50-120 cm, stout. |
Sheaths | closed for 1/6 – 1/4 their length, terete; ligules 1-3 mm, milky white to hyaline, smooth; blades 0.5-2 mm wide, flat or folded, or slightly inrolled, thin, without papillae (at 100x), apices narrowly prow-shaped. |
closed for 1/2 - 3/4 their length, distinctly compressed, keels winged, bases of basal sheaths glabrous; ligules 1-2 mm, smooth or sparsely scabrous, apices truncate; blades (4)6-15 mm wide, flat or folded, apices broadly and abruptly prow-shaped. |
Basal branching | all or mainly intra-vaginal. |
extravaginal. |
Panicles | 1-3 cm, erect, contracted, usually exserted from the sheaths; branches to 1.5 cm, erect to steeply ascending, slender, sulcate or angled, smooth or the angles sparsely scabrous; pedicels shorter than the spikelets. |
10-20 cm, ovoid to pyramidal, open, spikelets numerous, with 3-5 branches per node; branches ascending to spreading, angled, angles densely scabrous. |
Spikelets | 3-4 mm, laterally compressed, green or anthocyanic; florets 2-3; rachilla internodes shorter than 1 mm, smooth. |
4-9 mm, laterally compressed; florets 3-5; rachilla internodes about 1 mm, scabrous, glabrous. |
Glumes | usually equaling or exceeding the lowest lemmas, sometimes also equaling or exceeding the upper florets, lanceolate to broadly lanceolate, distinctly keeled, keels smooth; lower glumes 3-veined; calluses glabrous; lemmas 2.5-3 mm, lanceolate, distinctly keeled, thin, usually glabrous, keels and marginal veins rarely sparsely puberulent proximally, apices acute; palea keels scabrous; anthers 0.2-0.8 mm. |
distinctly keeled, keels scabrous; lower glumes 1-3-veined; calluses glabrous; lemmas 3.5-4.5 mm, narrowly lanceolate, distinctly keeled, scabrous, glabrous throughout, lateral veins prominent, apices acute; palea keels scabrous, glabrous; anthers 1.5-3 mm. |
2n | = 14. |
= 14. |
Poa lettermanii |
Poa chaixii |
|
Distribution |
CA; CO; ID; MT; NV; OR; UT; WA; WY; AB; BC
|
MN; NY; ON; QC |
Discussion | Poa lettermanii grows on rocky slopes of the highest peaks and ridges in the alpine zone, from northern British Columbia to western Alberta and south to California and Colorado, usually in the shelter of rocks or on mesic to wet, frost-scarred slopes. It is one of only three known diploid Poa species native to the Western Hemisphere. Its glabrous calluses and lemmas usually distinguish it from P. abbreviata (p. 582); it also differs in having flat or folded leaf blades, and shorter spikelets with glumes that are longer than the adjacent florets. Poa montevansii E.H. Kelso is tentatively included here, although its slightly longer lemmas that slightly exceed the glumes suggest that it may represent rare, glabrous forms of P. abbreviata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Poa chaixii was introduced from Europe as an attractive ornamental, and has occasionally escaped. A population in southwestern Quebec has been extirpated. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 24, p. 580. | FNA vol. 24, p. 540. |
Parent taxa | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Abbreviatae | Poaceae > subfam. Pooideae > tribe Poeae > Poa > subg. Poa > sect. Homalopoa |
Sibling taxa | ||
Synonyms | P. mor.tevansi | |
Name authority | Vasey | Vill. |
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