Achnatherum occidentale subsp. californicum

(Merr. & Burtt Davy) Barkworth
Common names: California needlegrass
Endemic
Synonyms: Stipa californica
Treatment appears in FNA Volume 24. Treatment on page 121.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Culms 30-100 (180) cm tall, 0.5-2 mm thick, internodes glabrous or pubescent, sometimes densely pubescent; nodes 2-4, glabrous or pubescent. Sheaths glabrous, pubescent, or pilose; collars usually with tufts of hair at the sides; blades 0.8-2 mm wide, usually erect or ascending, adaxial surfaces pilose. Panicles 8-30 cm; branches appressed, longest branches to 7 cm. Glumes usually green; lower glumes 0.6-0.8 mm wide; lemmas with hairs to 0.8 mm at midlength, apical hairs to 1.8 mm, longer than the basal awn hairs; awns 18-55 mm, scabrous or pilose on the first 2 segments, with hairs to 0.5 mm and of mixed lengths, terminal segment usually scabrous, occasionally pilose at the base. 2n = 36.

Discussion

Achnatherum occidentale subsp. californicum grows from Washington through Idaho to southwestern Montana and south to California and Nevada, with disjunct records from south-central Wyoming and southwestern Utah. Its elevation range is 2000-4000 m.

Johnson (1962) postulated that Achnatherum occidentale subsp. californicum is a hybrid derivative of A. nelsonii and A. occidentale; it intergrades with both. The scattering of longer hairs among shorter hairs on the basal awn segments, combined with the long apical lemma hairs, give florets of subsp. californicum a more untidy appearance than those of the other two subspecies. It resembles A. nevadense in this respect, but differs from that species in the shape of the boundary between the glabrous and strigose portions of the callus, in usually being glabrous below the lower cauline nodes, and in having paleas that are shorter in relation to the lemmas. Plants with scabrous awns are often confused with A. nelsonii subsp. nelsonii; they differ in having sharper calluses, a more elongated extension of the glabrous callus area into the strigose portion of the callus, and, usually, longer awns.

Selected References

None.

Lower Taxa

None.

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

membranous +  and scarious +
not penicillate +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
awned +, bifid +, bilobed +  and entire +
0 cm0 mm <br />0 m <br /> (0.18 cm1.8 mm <br />0.0018 m <br />) +
Mary E. Barkworth +
(Merr. & Burtt Davy) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
pilose +  and scabrous +
usually scabrous +  and scabridulous +
not once-geniculate +
1.8 cm18 mm <br />0.018 m <br /> (5.5 cm55 mm <br />0.055 m <br />) +
keeled +  and rounded +
puberulent +  and densely pubescent +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
straight +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.08 cm0.8 mm <br />8.0e-4 m <br />) +
not evident +
convolute +  and flat +
0.8mm;2mm +
spikelike +
well-developed +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
California needlegrass +
branching +  and not branching +
perennial +  and annual +
30 cm300 mm <br />0.3 m <br /> (100 cm1,000 mm <br />1 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 /> (0.2 cm2 mm <br />0.002 m <br />) +
Utah +, Wash. +, Colo. +, Mont. +, Alta. +, B.C. +, Idaho +, Calif. +, Wyo. +, Ariz. +, Nev. +  and Oreg. +
1/5 +  and 1/3 +
liquid +, soft +  and hard +
capillary +
pistillate +  and staminate +
0.55 cm5.5 mm <br />0.0055 m <br /> (0.75 cm7.5 mm <br />0.0075 m <br />) +
sometimes longer +
terete +  and fusiform +
9mm +  and 15mm +
subtending +
obtuse +, acute +  and acuminate +
subequal +
membranous +
0.6mm +  and 0.9mm +
divergent +  and distributed +
uncinate +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
solid +  and hollow +
pubescent +  and glabrous +
basally concentrated +  and evenly distributed +
0 cm0 mm <br />0 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
glabrous +  and hairy +
ovate +, rectangular +  and lanceolate +
stiffly membranous +  and coriaceous +
pubescent +  and glabrous +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
membranous +
membranous +
inconspicuous +
not lobed +
0 cm0 mm <br />0 m <br /> (7 cm70 mm <br />0.07 m <br />) +
0.6mm +  and 0.8mm +
concealed +  and prominent +
pubescent +  and glabrous +
2 +  and 4 +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
2/5 +  and 3/5 +
not keeled +
reduced +
0.22 cm2.2 mm <br />0.0022 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
5cm +  and 30cm +
8 cm80 mm <br />0.08 m <br /> (30 cm300 mm <br />0.3 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
dry +  and fleshy +
not prolonged +
pilose +, pubescent +  and glabrous +
1 +  and 60 +
unisexual +  and bisexual +
laterally compressed +  and terete +
1 (?) +  and 3 (?) +
simple +  and compound +
Stipa californica +
Achnatherum occidentale subsp. californicum +
Achnatherum occidentale +
subspecies +
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 +