Aristida dichotoma

Michx.
Common names: Churchmouse threeawn
Endemic
Treatment appears in FNA Volume 25. Treatment on page 328.

Plants annual. Culms 15-60 cm, erect or geniculate at the base, branching at most of the nodes. Leaves cauline; sheaths usually shorter than the internodes, glabrous or sparsely pilose; collars glabrous; ligules less than 0.5 mm; blades 3-10 cm long, 1-2 mm wide, flat to folded basally, involute distally, scabridulous on both surfaces, occasionally sparsely pilose adaxially, light green. Inflorescences paniculate or racemose, 2-11 cm long, to 1 cm wide; nodes glabrous or strigillose; primary branches 1-2 cm, appressed, without axillary pulvini, with 1-2 spikelets. Spikelets partly overlapping, often in pairs, 1 spikelet subsessile, the other pedicellate. Glumes 1-veined, light gray to dark purplish or brownish; lower glumes 3-8 (10) mm, from 1/2 as long as the upper glumes to nearly equaling them; upper glumes 4-13 mm; calluses 0.3-0.5 mm; lemmas 3-11 mm, light gray to purplish, frequently mottled, midveins scabrous, elsewhere glabrous, scabridulous, or sparsely appressed-puberulent, junction with the awns not evident; central awns 3-8 mm, coiled at the base, spreading distally; lateral awns 1-4 mm, straight, erect; anthers 3 and 2-3 mm, or 1 and about 0.25 mm. Caryopses light-brown. 2n = unknown.

Distribution

Conn., N.J., N.Y., Ill., Maine, Mich., Wis., W.Va., Del., D.C., Ohio, Ark., Kans., Nebr., Okla., S.Dak., Mass., N.H., R.I., Vt., Fla., Wyo., Tex., La., Ind., Miss., Tenn., N.C., S.C., Pa., Va., Colo., Ont., Calif., Ala., Ga., Iowa, Md., Mo., Minn., Ky.

Discussion

Aristida dichotoma grows in sandy fields and clearings, disturbed sites and sterile ground, pine woods, and on granitic outcrops of the United States and southern Ontario. The two varieties have similar ecological preferences and extensive overlap in their ranges, but var. curtissii is somewhat more western in its distribution.

Aristida dichotoma is similar to A. basiramea, differing in its shorter lateral awns. Further study may show that the two should be treated as conspecific varieties.

Selected References

None.

Key

1 Glumes unequal; lemmas smooth or scabridulous, 6-11 mm long Aristida dichotoma var. curtissii
1 Glumes equal or subequal; lemmas sparsely appressed-pubescent, 3-8 mm long Aristida dichotoma var. dichotoma

"decumbent" is not a number.

... more about "Aristida dichotoma"
1 +  and 3 +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
Kelly W. Allred +
Michx. +
1 (?) +  and 3 (?) +
straight +
ascending +  and spreading +
not evident +
keeled +  and rounded +
coiled +, disarticulating +  and twisted +
intravaginal +, extravaginal +, branching +  and basal +
swelling +
straight +
light green +
3 cm30 mm <br />0.03 m <br /> (10 cm100 mm <br />0.1 m <br />) +
scabridulous +
flat +  and folded basally +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
spikelike +
well-developed +
0.03 cm0.3 mm <br />3.0e-4 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
non-radiate +  and radiate +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
Churchmouse threeawn +
geniculate +
15 cm150 mm <br />0.15 m <br /> (60 cm600 mm <br />0.6 m <br />) +
not woody +
Conn. +, N.J. +, N.Y. +, Ill. +, Maine +, Mich. +, Wis. +, W.Va. +, Del. +, D.C. +, Ohio +, Ark. +, Kans. +, Nebr. +, Okla. +, S.Dak. +, Mass. +, N.H. +, R.I. +, Vt. +, Fla. +, Wyo. +, Tex. +, La. +, Ind. +, Miss. +, Tenn. +, N.C. +, S.C. +, Pa. +, Va. +, Colo. +, Ont. +, Calif. +, Ala. +, Ga. +, Iowa +, Md. +, Mo. +, Minn. +  and Ky. +
large +  and small +
capillary +
germination +
pistillate +  and staminate +
sometimes longer +
compressed +  and terete +
light gray +  and dark purplish or brownish +
subtending +
acute +  and acuminate +
racemose +  and paniculate +
2 cm20 mm <br />0.02 m <br /> (?) +  and 11 cm110 mm <br />0.11 m <br /> (?) +
0 cm0 mm <br />0 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
mottled +, light gray +  and purplish +
scabridulous +
fusiform +
0.3 cm3 mm <br />0.003 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
coriaceous +
indistinguishable +
0 cm0 mm <br />0 m <br /> (0.05 cm0.5 mm <br />5.0e-4 m <br />) +
inconspicuous +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
appressed-puberulent +  and glabrous +
scabridulous +
concealed +  and prominent +
strigillose +  and glabrous +
2 +  and 1 +
concealing +
0 +  and 1/2 +
dry +  and fleshy +
divaricate +  and divergent +
ascending;usually appressed;ascending +
1 cm10 mm <br />0.01 m <br /> (2 cm20 mm <br />0.02 m <br />) +
not prolonged +
pilose +  and glabrous +
1 (?) +  and Anatomy (?) +
pedicellate +  and subsessile +
1 +  and 3 +
triangular +  and dome--shaped +
2 (?) +  and 3 (?) +
Gramineae +
Aristida dichotoma +
Aristida +
species +
membranous +
0.4 cm4 mm <br />0.004 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
aquatic +  and terrestrial +