Piptatherum canadense
Piptatherum pungens
Canada mountain-rice grass, Canadian piptatherum, Canadian ricegrass, oryzopsis du Canada
mountain ricegrass, sharp piptatherum, short-awn mountain-rice grass
30-90 cm, glabrous;
basal branching mostly intravaginal.
10-90 cm, usually glabrous, occasionally puberulent beneath the nodes;
basal branching intravaginal.
basally concentrated;
sheaths smooth or scabridulous;
ligules 1-4 mm, hyaline, truncate, rounded, or acute;
basal blades 4-15 cm long, 1-1.5 mm wide when flat, 0.5-0.8 mm in diameter when folded or convolute.
basally concentrated;
sheaths smooth or somewhat scabrous;
ligules 0.5-2.5 mm, truncate to acute;
blades (6)18-45 cm long, 0.5-1.8 mm wide, flat to convolute, abaxial surfaces scabridulous to scabrous, adaxial surfaces scabrous.
9-15 cm, lower nodes with 1-2 branches;
branches 1-6 cm, somewhat flexuous, ascending to divergent.
4-6 cm, lower nodes with 1-2 primary branches;
branches 0.8-4 cm, straight, usually strongly ascending, ascending to divergent at anthesis.
subequal, 3-6 mm long, 1.3-2 mm wide, ovate, 1-3-veined, apices acute to mucronate;
florets 2.2-4.5 mm, obovoid, dorsally compressed;
calluses 0.2-0.5 mm, hairy, disarticulation scars elliptic;
lemmas coriaceous, evenly pubescent, tan at maturity, margins widely separated even when immature;
awns 5-15 mm, persistent, once- or twice-geniculate, first segments strongly twisted;
paleas similar to the lemmas in length, texture, and pubescence;
anthers 1-2 mm;
ovaries developing 2 conelike style bases, each bearing a single, unbranched style.
subequal, 3.5-4.5 mm long, 1.4-2 mm wide, from 1 mm shorter than to slightly exceeding the florets, ovate, usually 1-veined, sometimes 3-5-veined near the base, apices rounded or acute;
florets 3-4 mm, dorsally compressed;
calluses 0.2-0.3 mm, rounded, hairy, disarticulation scars circular;
lemmas evenly pubescent, margins not overlapping at maturity;
awns 1-2 mm, straight, slightly twisted, caducous, often absent even from immature florets;
paleas equaling or almost equaling the lemma lobes, similar in texture and pubescence to the lemmas;
anthers 0.8-1.8 mm, usually not penicillate;
ovaries with a conelike extension bearing a 2-branched style.
about 2.5 mm long, 0.5 mm thick;
hila linear, almost equaling the caryopses.
about 1.8 mm long, about 0.9 mm wide;
hila linear, 9/10 as long as to equaling the caryopses.
= 22.
= 22, 24.
Piptatherum canadense
Piptatherum pungens
Piptatherum canadense grows in grasslands and open woods, from the British Columbia-Alberta border east to Newfoundland, extending south into the Great Lakes region and the northeastern United States. Its persistent, longer awns distinguish P. canadense from P. pungens.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Piptatherum pungens grows in sandy to rocky soils and open habitats, from southern Yukon Territory across Canada to the Great Lakes region and eastern Pennsylvania, and, as a disjunct, in the western Great Plains and the southern Rocky Mountains. Its apparent absence from Idaho and Montana, and almost complete absence from Wyoming, is puzzling. The awns of P. pungens fall off so rapidly that it is sometimes mistaken for Milium or Agrostis, but the only perennial species of Milium in the Flora region has leaf blades 8-17 mm wide, and no species of Agrostis has such stiff lemmas and well-developed paleas. Its deciduous, shorter awns distinguish it from P. canadense.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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