Piptatherum micranthum
Piptatherum racemosum
little-seed mountain-rice grass, littleseed ricegrass, piptatherum micranthum, small-flower piptatherum
black-seed mountain-rice grass, mountain ricegrass
20-85 cm, glabrous;
basal branching extravaginal.
48-80 cm, scabrous or pubescent adjacent to the nodes;
basal branching extravaginal.
basally concentrated;
sheaths glabrous;
ligules 0.4-1.5(2.5) mm, truncate;
blades 5-16 cm long, 0.5-2.5 mm wide, usually involute.
not basally concentrated;
sheaths usually smooth and glabrous, occasionally scabridulous and inconspicuously pubescent near the margins;
ligules of upper leaves 0.3-0.7 mm, truncate;
blades of basal leaves 0-2 cm;
blades of upper leaves 10-27 cm long, 8-16 mm wide, abaxial surfaces evenly but sparsely pubescent, adaxial surfaces with straight hairs to 0.3 mm on the primary veins and flexuous hairs of 0.5-0.9 mm on the minor veins, tapering from near midlength to the apices.
5-20 cm, lower nodes with 1-3 branches;
branches 2-6 cm, divergent to reflexed at maturity, with 3-10(15) spikelets, secondary branches appressed to the primary branches.
12-25 cm, lower nodes with 1-2 branches;
branches 3-9.5 cm, straight, strongly ascending to strongly divergent, with 2-5 spikelets.
2.5-3.5 mm, acute;
lower glumes 1(3)-veined;
upper glumes 3-veined;
florets 1.5-2.5 mm, dorsally compressed;
calluses 0.1-0.2 mm, glabrous or sparsely hairy, disarticulation scars circular;
lemmas usually glabrous, sometimes sparsely pubescent, brownish, shiny, 5-veined, margins not overlapping at maturity;
awns 4-8 mm, straight or almost so, caducous;
anthers 0.6-1.2 mm, not penicillate;
ovaries truncate to rounded, bearing 2 separate styles.
6-8 mm, from subequal to the florets to exceeding the florets by 2 mm, ovate, 5-7-veined, acuminate;
florets 4.5-7.5 mm;
calluses 0.3-0.6 mm, disarticulation scars circular;
lemmas coriaceous, sparsely pubescent to glabrate throughout, margins fused at the base, not overlapping, shiny dark brown to black at maturity;
awns 10-25 mm, deciduous, slightly twisted, flexuous;
anthers 3.5-5.5 mm, not penicillate;
ovaries developing 2 conelike extensions, each terminating in a style.
about 1.2 mm long, about 0.8 mm wide;
hila linear, 3/4 - 9/10 as long as the caryopses.
5-6 mm;
hila linear, 4/5 – 9/10 as long as the caryopses.
= 22.
= 46,48.
Piptatherum micranthum
Piptatherum racemosum
Piptatherum micranthum grows on gravel benches, rocky slopes, and creek banks, from British Columbia to Manitoba and south to Arizona, New Mexico, and western Texas. The combination of small, dorsally compressed florets and appressed pedicels distinguishes this species from all other native North American Stipeae. Achnatherum contractum is the fertile derivative of hybridization between Piptatherum micranthum and A. hymenoides. It is placed in Achnatherum because it resembles that genus more than Piptatherum.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Piptatherum racemosum usually grows in deciduous woods, and less often in open pine woods, in rocky, mountainous areas, from the St. Lawrence and Ottawa rivers south to the Missouri River, Tennessee, and Virginia, and east to Maine. The absence of basal blades and the dark, shiny lemmas distinguish it from all other North American Stipeae. It is highly palatable to livestock, but is never sufficiently abundant to be important as forage.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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