Achnatherum hymenoides

(Roem. & Schult.) Barkworth
Common names: Indian ricegrass
Synonyms: Stipa hymenoides Oryzopsis hymenoides
Treatment appears in FNA Volume 24. Treatment on page 139.
Revision as of 02:47, 30 July 2020 by imported>Volume Importer
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants tightly cespitose, not rhizomatous. Culms 25-70 cm tall, 0.7-1.3 mm thick, glabrous or partly scabridulous; nodes 3-4. Sheaths glabrous or scabridulous, sometimes puberulent on the distal margins, hairs to 0.8 mm; collars glabrous, sometimes with tufts of hair on the sides, hairs to 1 mm; basal ligules 1.5-4 mm, hyaline, glabrous, acute; upper ligules to 2 mm; blades usually convolute, 0.1-1 mm in diameter, abaxial surfaces smooth or scabridulous, adaxial surfaces pubescent. Panicles 9-20 cm long, 8-14 cm wide; branches ascending to strongly divergent, longest branches 3-15 cm; pedicels paired, conspicuously divaricate, shorter pedicels in each pair usually at least 1/2 as long as the longer pedicels. Glumes subequal, 5-9 mm long, 0.8-2 mm wide, saccate below, puberulent, hairs about 0.1 mm, tapering above midlength, apices acuminate; lower glumes 5-veined at the base, 3-veined at midlength; upper glumes 5-7-veined at the base; florets 3-4.5 mm long, 1-2 mm thick, obovoid; calluses 0.4-1 mm, sharp; lemmas indurate, densely and evenly pilose, hairs 2.5-6 mm, easily rubbed off, apices not lobed; awns 3-6 mm, rapidly deciduous, not geniculate, scabrous; paleas subequal to the lemmas in length and texture, glabrous, apices pinched; anthers 1.5-2 mm, penicillate, dehiscent, well-filled. Caryopses 2-3 mm. 2n = 46, 48.

Distribution

Colo., N.Mex., Tex., Utah, Calif., Minn., Kans., N.Dak., Nebr., Okla., S.Dak., Oreg., Mont., Alta., B.C., Man., Sask., Yukon, Ark., Wyo., Wash., Ariz., Idaho, Nev.

Discussion

Achnatherum hymenoides grows in dry, well-drained soils, primarily in the western part of the Flora region and northern Mexico. Specimens from further east may be introduced; it is unknown whether they have persisted. The roots of A. hymenoides are often surrounded by a rhizosheath formed by mucilaginous secretions to which soil particles attach. This rhizosheath harbors nitrogen-fixing organisms that probably contribute to the success of the species as a colonizer.

Native Americans used the seeds of Achnatherum hymenoides for food. It is also one of the most palatable native grasses for livestock. Several cultivars have been developed for use in restoration work, and it is becoming increasingly available for use as an ornamental.

Achnatherum hymenoides forms natural hybrids with other members of the Stipeae. See discussion on p. 142.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum hymenoides"
scabridulous +  and smooth +
membranous +  and scarious +
penicillate +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
awned +, bifid +, bilobed +  and entire +
0 cm0 mm <br />0 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
Mary E. Barkworth +
(Roem. & Schult.) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not geniculate +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
involute +, convolute +  and flat +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
flexuous +  and straight +
spikelike +
well-developed +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Indian ricegrass +
branching +  and not branching +
perennial +  and annual +
25 cm250 mm <br />0.25 m <br /> (70 cm700 mm <br />0.7 m <br />) +
intravaginal +  and basal +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.13 cm1.3 mm <br />0.0013 m <br />) +
Colo. +, N.Mex. +, Tex. +, Utah +, Calif. +, Minn. +, Kans. +, N.Dak. +, Nebr. +, Okla. +, S.Dak. +, Oreg. +, Mont. +, Alta. +, B.C. +, Man. +, Sask. +, Yukon +, Ark. +, Wyo. +, Wash. +, Ariz. +, Idaho +  and Nev. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.3 cm3 mm <br />0.003 m <br /> (0.45 cm4.5 mm <br />0.0045 m <br />) +
sometimes longer +
5mm +  and 9mm +
subtending +
obtuse +, acute +  and acuminate +
subequal +
membranous +
0.8mm +  and 2mm +
divergent +  and distributed +
lobed +  and tapering +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
solid +  and hollow +
basally concentrated +  and evenly distributed +
0 cm0 mm <br />0 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
ovate +, rectangular +  and lanceolate +
pubescent +  and glabrous +
membranous +
membranous +
inconspicuous +
not lobed +
3 cm30 mm <br />0.03 m <br /> (15 cm150 mm <br />0.15 m <br />) +
3-veined +  and 5-veined +
concealed +  and prominent +
3 +  and 4 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
not keeled +
subequal +
9cm +  and 20cm +
8 cm80 mm <br />0.08 m <br /> (14 cm140 mm <br />0.14 m <br />) +
divaricate +  and paired +
dry +  and fleshy +
not prolonged +
puberulent +  and glabrous +
scabridulous +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa hymenoides +  and Oryzopsis hymenoides +
Achnatherum hymenoides +
Achnatherum +
species +
membranous +
inconspicuous +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
plant +  and cespitose +
aquatic +  and terrestrial +