Trisetum flavescens

(L.) P. Beauv.
Common names: Yellow oatgrass Avoine jaunâtre
Introduced
Treatment appears in FNA Volume 24. Treatment on page 748.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants perennial, sometimes with both fertile and sterile shoots; usually cespitose, sometimes rhizomatous, rhizomes usually short, to 7 cm in sandy soils. Culms (10) 50-80 (130) cm, solitary or clumped, erect or decumbent, glabrous, sometimes scabrous or pubescent near the upper nodes. Leaves usually evenly distributed; sheaths glabrous or pilose, throats often with 2+ mm hairs; ligules 0.5-1 (2) mm, obtuse, lacerate, sometimes ciliolate, hairs to 0.5 mm; blades 5-15 (18) cm long, 1.5-4 (6) mm wide, flat or involute, lax, pubescent or pilose. Panicles 5-20 cm long, 1.5-7 cm wide, erect or nodding, glistening yellowish-brown, sometimes purple-tinged or variegated; branches 2-4 (6) cm, ascending to divergent, often flexuous, sometimes naked below. Spikelets 4-8 mm, subsessile or on pedicels to 5 mm, with (2) 3 (4) florets; rachilla internodes to 1+ mm; rachilla hairs to 1.5 mm; disarticulation above the glumes, beneath the florets. Glumes unequal, shiny; lower glumes 2.5-4.7 mm, narrowly lanceolate to subulate; upper glumes 4-7 mm long, as long as or longer than the lowest florets, twice as wide as the lower glumes, lance-elliptic, acute; callus hairs to 0.5 mm; lemmas 3.5-6.3 mm, ovatelanceolate, minutely pubescent, bifid or bicuspidate, teeth conspicuous, usually 3-6 mm, awned, awns (3) 5-9 mm, arising from the upper 1/3 of the lemmas and exceeding the apices, geniculate, tightly twisted below; paleas 3-5.5 mm; anthers 1.3-2.8 mm. Caryopses 2.5-3 mm, glabrous. 2n = 28.

Distribution

N.J., Mass., Wash., Calif., Kans., N.Y., Pacific Islands (Hawaii), Vt., Miss., Okla., Alta., B.C., N.S., Ont., Que., Mo.

Discussion

Trisetum flavescens grows in seeded pastures, roadsides, and as a weed in croplands. Native to Europe, west Asia, and north Africa, it was introduced into the Flora region because of its drought resistance, wide soil tolerance, and high palatability to domestic livestock. It is one of the few range plants known to contain calcinogenic glycosides, which can lead to vitamin D toxicity in grazing animals (Dixon 1995). This species seems not to have persisted in southern Ontario (Michael Oldham, pers. comm.). Several infraspecific taxa have been recognized; no attempt has been made to determine which are present in the Flora region.

Selected References

None.

Lower Taxa

None.

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

... more about "Trisetum flavescens"
membranous +  and scarious +
0.13 cm1.3 mm <br />0.0013 m <br /> (0.28 cm2.8 mm <br />0.0028 m <br />) +
entire +, bifid +  and apiculate +
John H. Rumely +
(L.) P. Beauv. +
1 (?) +  and 3 (?) +
3 cm30 mm <br />0.03 m <br /> (?) +
straight +
basal +  and terminal +
geniculate +
0.5 cm5 mm <br />0.005 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
5 cm50 mm <br />0.05 m <br /> (15 cm150 mm <br />0.15 m <br />) +
not evident +
pilose +  and pubescent +
involute +  and flat +
1.5mm;4mm +
6 cm60 mm <br />0.06 m <br /> (?) +
spikelike +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
Yellow oatgrass +  and Avoine jaunâtre +
clumped +  and solitary +
decumbent +  and erect +
extravaginal +  and basal +
pubescent +, scabrous +  and glabrous +
50 cm500 mm <br />0.5 m <br /> (80 cm800 mm <br />0.8 m <br />) +
not woody +
N.J. +, Mass. +, Wash. +, Calif. +, Kans. +, N.Y. +, Pacific Islands (Hawaii) +, Vt. +, Miss. +, Okla. +, Alta. +, B.C. +, N.S. +, Ont. +, Que. +  and Mo. +
0 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
sterile +  and bisexual +
compressed +
reduced +
shorter or longer +
subtending +
unequal +
uncinate +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
diffuse +  and dense +
distributed +
bicuspidate +  and bifid +
ovatelanceolate +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.63 cm6.3 mm <br />0.0063 m <br />) +
lacerate +  and obtuse +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
membranous +
inconspicuous +
usually slenderly lobed +  and fimbriate +
narrowly lanceolate +  and subulate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.47 cm4.7 mm <br />0.0047 m <br />) +
concealed +  and prominent +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
2-keeled +
subequal +  and longer +
0.3 cm3 mm <br />0.003 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
membranous +
variegated +, purple-tinged +  and yellowish-brown +
5cm +  and 20cm +
nodding +  and erect +
spikelike +
1.5 cm15 mm <br />0.015 m <br /> (7 cm70 mm <br />0.07 m <br />) +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
dry +  and fleshy +
0 cm0 mm <br />0 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
pilose +  and glabrous +
sterile +  and fertile +
Introduced +
on pedicels +  and subsessile +
1 +  and 60 +
compressed +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
1 (?) +  and 3 (?) +
simple +  and compound +
2 (?) +  and 3 (?) +
Gramineae +
Trisetum flavescens +
Trisetum +
species +
bristlelike +
membranous +
conspicuous +
0.3 cm3 mm <br />0.003 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
2 times as wide as the lower glumes +
parallel +  and converging +
plant +  and cespitose +
aquatic +  and terrestrial +