Achnatherum perplexum

Hoge & Barkworth
Common names: Perplexing needlegrass
Treatment appears in FNA Volume 24. Treatment on page 135.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants cespitose, not rhizomatous. Culms 35-90 cm tall, 0.7-2.2 mm thick, lower internodes glabrous, puberulent to 5 mm below the nodes; nodes 2-3. Basal sheaths mostly glabrous, margins ciliolate distally; collars glabrous, including the sides; basal ligules 0.2-0.5 mm, truncate, ciliolate, cilia to 0.1 mm; upper ligules 0.2-3.5 mm, rounded to acute; blades to 30 cm long, 1-3 mm wide. Panicles 10-25 cm long, 0.5-1.5 cm wide; branches ascending to appressed, straight. Spikelets appressed to the branches. Glumes unequal; lower glumes 10-15 mm long, 0.5-1.1 mm wide, exceeding the upper glumes by 1-3 (4) mm; florets 5.5-11 mm long, 0.7-1 mm thick, fusiform, terete, widest at or below midlength; calluses 0.4-0.6 mm, blunt; lemmas evenly hairy, hairs at midlength about 1 mm, apical hairs 1-2 mm, ascending to divergent, apical lobes 0.2-0.5 mm, membranous, flexible; awns 10-19 mm, persistent, once (twice) -geniculate, basal segments scabrous, terminal segments straight; paleas 2.8-5.6 mm, 1/2 -2/3 as long as the lemmas, hairy, hairs not or scarcely exceeding the apices, veins terminating at or before the apices, apices acute to rounded; anthers 2.5-4 mm, dehiscent, not penicillate. Caryopses 3-6 mm, fusiform. 2n = unknown.

Discussion

Achnatherum perplexum grows on slopes in pinyon-pine associations of the southwestern United States and adjacent Mexico, at 1500-1700 m. It flowers in late summer to early fall. It has generally been confused with A. scribneri, A. nelsonii, and A. lobatum. It differs from A. scribneri in the glabrous collar margins of its basal leaves and its blunt calluses; from A. nelsonii and A. lettermanii in its unequal glumes; from A. lettermanii in its relatively short paleas; and from A. lobatum in its shorter lemma lobes and ascending to divergent apical lemma hairs.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum perplexum"
membranous +  and scarious +
not penicillate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
awned +, bifid +, bilobed +  and entire +
Rounded (?) +  and Acute (?) +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Mary E. Barkworth +
Hoge & Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
once-geniculate +
1 cm10 mm <br />0.01 m <br /> (1.9 cm19 mm <br />0.019 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
0 cm0 mm <br />0 m <br /> (30 cm300 mm <br />0.3 m <br />) +
not evident +
involute +, convolute +  and flat +
1mm;3mm +
ascending;appressed +
spikelike +
well-developed +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.06 cm0.6 mm <br />6.0e-4 m <br />) +
0 cm0 mm <br />0 m <br /> (0.01 cm0.1 mm <br />1.0e-4 m <br />) +
Perplexing needlegrass +
branching +  and not branching +
perennial +  and annual +
35 cm350 mm <br />0.35 m <br /> (90 cm900 mm <br />0.9 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 /> (0.22 cm2.2 mm <br />0.0022 m <br />) +
Ariz. +, Utah +, N.Mex. +  and Tex. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.55 cm5.5 mm <br />0.0055 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
sometimes longer +
terete +  and fusiform +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
unequal +
membranous +
divergent +  and distributed +
uncinate +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 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 +
stiffly membranous +  and coriaceous +
pubescent +  and glabrous +
membranous +
membranous +
inconspicuous +
not lobed +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
0.5mm +  and 1.1mm +
puberulent +  and glabrous +
0 cm0 mm <br />0 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
concealed +  and prominent +
2 +  and 3 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
1/2 +  and 2/3 +
not keeled +
reduced +
0.28 cm2.8 mm <br />0.0028 m <br /> (0.56 cm5.6 mm <br />0.0056 m <br />) +
10cm +  and 25cm +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
dry +  and fleshy +
not prolonged +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Gramineae +
Achnatherum perplexum +
Achnatherum +
species +
membranous +
inconspicuous +
Acute (?) +  and Rounded (?) +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
plant +  and cespitose +
aquatic +  and terrestrial +