Achnatherum scribneri

(Vasey) Barkworth
Common names: Scribner's needlegrass
Synonyms: Stipa scribneri
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 25-90 cm tall, 0.5-1.6 mm thick, glabrous; nodes 3. Basal sheaths becoming flat and papery, margins ciliate distally; collars glabrous, with tufts of hair on the sides, hairs on the basal leaves to 1.5 mm, hairs on the flag leaves 1-2.5 mm; basal ligules 0.3-0.8 mm, truncate, erose, ciliate, cilia 0.2-0.4 mm; upper ligules to 1.5 mm, asymmetric, obliquely truncate for most of their width, abruptly longer on 1 side; blades to 30 cm long, 2-5 mm wide, flat or involute, long-tapering. Panicles 7-21 cm long, 0.5-1 cm wide; branches appressed to ascending, straight. Lower glumes 10-17 mm long, 0.7-1.2 mm wide, exceeding the upper glumes by 2.5-4.5 mm, apices tapering, often slightly recurved; florets 6-9.5 mm long, 0.6-1.1 mm thick, fusiform, terete, widest at or below midlength; calluses 0.5-1.5 mm, sharp; lemmas evenly hairy, hairs at midlength to 1 mm, apical hairs 2-3 mm, ascending, apical lobes 0.3-0.5 mm; awns 13-25 mm, persistent, usually once-geniculate, first segment scabrous, terminal segment straight; paleas 2.5-3.5 mm, 1/3 – 1/2 as long as the lemmas, pubescent, hairs not exceeding the apices, apices rounded; anthers 3-5 mm, dehiscent, not penicillate. Caryopses 5-6 mm, fusiform. 2n = 40.

Distribution

Okla., Wyo., Colo., N.Mex., Tex.

Discussion

Achnatherum scribneri grows on rocky slopes, in pinyon-juniper and ponderosa pine associations at 1500-2700 m, from southeastern Wyoming through Colorado to Arizona, New Mexico, western Oklahoma, and Texas, and in Capital Reef National Park, Utah. At present, the Utah population appears to be disjunct from the species' primary range; this may reflect a lack of collecting. Achnatherum scribneri is similar to A. parishii, A. robustum, A. perplexum, and A. lobatum, differing from all of them in its sharp calluses.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum scribneri"
membranous +  and scarious +
not penicillate +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
awned +, bifid +, bilobed +  and entire +
Rounded (?) +  and Tapering (?) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
Mary E. Barkworth +
(Vasey) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
once-geniculate +
1.3 cm13 mm <br />0.013 m <br /> (2.5 cm25 mm <br />0.025 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 +
long-tapering +, involute +  and flat +
2mm;5mm +
appressed;ascending +
spikelike +
well-developed +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.04 cm0.4 mm <br />4.0e-4 m <br />) +
Scribner's needlegrass +
branching +  and not branching +
perennial +  and annual +
25 cm250 mm <br />0.25 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 +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.16 cm1.6 mm <br />0.0016 m <br />) +
Okla. +, Wyo. +, Colo. +, N.Mex. +  and Tex. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.6 cm6 mm <br />0.006 m <br /> (0.95 cm9.5 mm <br />0.0095 m <br />) +
sometimes longer +
terete +  and fusiform +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
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 +
0.1 cm1 mm <br />0.001 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
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 /> (1.7 cm17 mm <br />0.017 m <br />) +
0.7mm +  and 1.2mm +
concealed +  and prominent +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
1/3 +  and 1/2 +
not keeled +
reduced +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
7cm +  and 21cm +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
dry +  and fleshy +
not prolonged +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa scribneri +
Achnatherum scribneri +
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 +