Achnatherum stillmanii

(Bol.) Barkworth
Common names: Stuxman's needlegrass
Endemic
Synonyms: Stipa stillmanii
Treatment appears in FNA Volume 24. Treatment on page 118.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants shortly rhizomatous, forming open clumps. Culms 60-150 cm tall, 2-5 mm thick, often geniculate at the lowest node, mostly glabrous; nodes 2-3, often puberulent. Basal sheaths mostly glabrous, some¬times ciliate distally, intact at maturity; collars glabrous or pubescent, often with hairs at the sides, hairs shorter than 0.5 mm; basal ligules 0.2-0.5 mm, membranous, truncate, ciliate, cilia 0.2-0.3 mm; upper ligules shorter than the basal ligules; blades 3-7 mm wide, lax. Panicles 10-24 cm long, 1.5-3 cm wide, contracted; branches straight, appressed to strongly ascending, lower branches 2.5-3.5 cm. Spikelets appressed to the branches. Glumes subequal, 14-16 mm; lower glumes 1-3-veined; upper glumes 0.6-1.5 mm wide, 3-5-veined; florets 8-10 mm, fusiform; calluses 0.5-1.2 mm, rounded; lemmas evenly hairy, hairs about 0.5 mm, apical hairs similar in length, apices 2-lobed, lobes 1-3 mm, narrow; awns 18-25 mm, persistent, scabrous, once or twice-geniculate, terminal segment straight; paleas as long as or slightly longer than the lemmas, hairy, hairs about 0.5 mm, veins prolonged, reaching almost to the tips of the lemma lobes; anthers 4-6 mm, penicillate, dehiscent. Caryopses fusiform. 2n = unknown.

Discussion

Achnatherum stillmanii grows at scattered locations in coniferous forests in northern California, at 900-1500 m, possibly being edaphically restricted. Its combination of large size, long, narrow lemma lobes, and paleal morphology distinguish A. stillmanii from all other North American species of Achnatherum.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum stillmanii"
membranous +  and scarious +
penicillate +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 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 +
(Bol.) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
usually scabrous +  and scabridulous +
not once-geniculate +
1.8 cm18 mm <br />0.018 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
keeled +  and rounded +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
involute +, convolute +  and flat +
3mm;7mm +
appressed;strongly ascending +
spikelike +
well-developed +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
pubescent +  and glabrous +
Stuxman's needlegrass +
branching +  and not branching +
perennial +  and annual +
60 cm600 mm <br />0.6 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
intravaginal +  and basal +
geniculate +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
sometimes longer +
fusiform +
8mm +  and 10mm +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
subequal +
1.4 cm14 mm <br />0.014 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
membranous +
divergent +  and distributed +
uncinate +
0.5 cm5 mm <br />0.005 m <br /> (0.5 cm5 mm <br />0.005 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 +
2.5 cm25 mm <br />0.025 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
concealed +  and prominent +
puberulent +
2 +  and 3 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
not keeled +
reduced +
10cm +  and 24cm +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
dry +  and fleshy +
not prolonged +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa stillmanii +
Achnatherum stillmanii +
Achnatherum +
species +
membranous +
0.6mm +  and 1.5mm +
inconspicuous +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
aquatic +  and terrestrial +