Achnatherum diegoense

(Swallen) Barkworth
Common names: San diego needlegrass
Treatment appears in FNA Volume 24. Treatment on page 131.
Please click on the illustration for a higher resolution version.
Illustrator: Cindy Roché

Copyright: Utah State University

Plants cespitose, not rhizomatous. Culms 110-140 cm tall, 2.5-4 mm thick, internodes densely and retrorsely pubescent for 3-9 mm below the nodes, particularly the lower nodes, glabrous or retrorsely puberulent elsewhere; nodes 3, pubescent or glabrate. Basal sheaths mostly glabrous or puberulent, margins ciliate distally; collars glabrous or with hairs, hairs mostly to 0.5 mm, sides with tufts of 1.5-2 mm hairs; ligules 0.4-2 mm, rounded to acute, abaxial surfaces hairy, hairs to 0.5 mm; upper ligules 1-3 mm, similar in structure and pubescence; blades 1-3.5 mm wide, abaxial surfaces smooth or scabrous, adaxial surfaces prominently ribbed, hairy, hairs 2-3 mm. Panicles 21-25 cm long, (2) 4-8 cm wide; branches strongly divergent to ascending, straight, lower branches 5-7 cm. Spikelets appressed to the branches. Glumes subequal, 8-11.5 mm; lower glumes 0.5-1 mm wide, 3-5-veined; upper glumes 3-veined; florets 5.5-7.5 mm long, 0.7-1 mm thick, fusiform, terete; calluses 0.25-1.2 mm, acute; lemmas evenly hairy, hairs at midlength and at the apices 0.5-1 mm, apical lobes 0.2-0.4 mm, membranous, flexible; awns 20-50 mm, persistent, twice-geniculate, all segments scabrous to scabridulous, terminal segment straight; paleas 2.6-3.8 mm, 1/2 - 3/4 as long as the lemmas, pubescent, hairs not extending beyond the apices, veins terminating below the apices, apices rounded; anthers 2.5-4 mm, dehiscent, not penicillate. 2n = unknown.

Discussion

Achnatherum diegoense grows in chaparral and coastal sage scrub, on rocky soil near streams or the coast, at 0-350 m, on the Channel Islands of Santa Barbara County, California, and, on the mainland, in Ventura and San Diego counties south into Baja California, Mexico.

Selected References

None.

Lower Taxa

None.

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

... more about "Achnatherum diegoense"
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 +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
0 cm0 mm <br />0 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
Mary E. Barkworth +
(Swallen) Barkworth +
1 (?) +  and 3 (?) +
flexuous +
subterminal +  and eccentric +
scabrous +  and scabridulous +
not once-geniculate +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
keeled +  and rounded +
puberulent +  and glabrous +
pseudopetiolate +  and branching +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
not evident +
involute +, convolute +  and flat +
1mm;3.5mm +
spikelike +
well-developed +
0.025 cm0.25 mm <br />2.5e-4 m <br /> (0.12 cm1.2 mm <br />0.0012 m <br />) +
with hairs +  and glabrous +
San diego needlegrass +
branching +  and not branching +
perennial +  and annual +
110 cm1,100 mm <br />1.1 m <br /> (140 cm1,400 mm <br />1.4 m <br />) +
intravaginal +  and basal +
10 cm100 mm <br />0.1 m <br /> (250 cm2,500 mm <br />2.5 m <br />) +
not woody +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
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 +
1-10-veined +
subtending +
obtuse +, acute +  and acuminate +
subequal +
0.8 cm8 mm <br />0.008 m <br /> (1.15 cm11.5 mm <br />0.0115 m <br />) +
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 +
puberulent +, glabrous +  and pubescent +
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 +
rounded +  and acute +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
membranous +
membranous +
inconspicuous +
not lobed +
5 cm50 mm <br />0.05 m <br /> (7 cm70 mm <br />0.07 m <br />) +
0.5mm +  and 1mm +
concealed +  and prominent +
glabrate +  and pubescent +
2 +  and 1 +
pubescent +  and glabrous +
well-developed +
1/2 +  and 3/4 +
not keeled +
reduced +
0.26 cm2.6 mm <br />0.0026 m <br /> (0.38 cm3.8 mm <br />0.0038 m <br />) +
21cm +  and 25cm +
4 cm40 mm <br />0.04 m <br /> (8 cm80 mm <br />0.08 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 diegoense +
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 +