Eriochloa acuminata
Eriochloa contracta
Southwestern cupgrass, taper-tip cup grass
dense cupgrass, prairie cup grass
30-120 cm, erect or decumbent, sometimes rooting at the lower nodes;
internodes glabrous or with scattered hairs;
nodes glabrous or pilose.
20-100 cm, erect or decumbent, sometimes rooting at the lower nodes;
internodes pilose or pubescent;
nodes pubescent to puberulent.
some times conspicuously inflated, glabrous or pubescent;
ligules 0.2-1.2 mm;
blades 5-12(18) cm long, (2)5-12(16) mm wide, linear, flat or folded, straight or lax, glabrous or sparsely pubescent adaxially.
sparsely to densely pubescent;
ligules 0.4-1.1 mm;
blades 6-12(22) cm long, 2-8 mm wide, linear, flat to conduplicate, straight, appressed to divergent, both surfaces sparsely to densely pubescent with short, evenly spaced hairs.
7-16 cm long, 1-6 cm wide, loosely contracted;
rachises scabrous or hairy;
branches 5-20, 1-5 cm long, 0.4-0.6 mm wide, appressed to divergent, pubescent, sometimes setose, not winged, with 20-36 spikelets, spikelets mostly in unequally pedicellate pairs, solitary distally;
pedicels 0.1-1 mm, hairy.
6-20 cm long, 0.3-1.2 cm wide;
rachises pilose, longer hairs 0.1-0.8 mm;
branches 10-20(28), 15-45(60) mm long, 0.2-0.4 mm wide, appressed, pubescent to setose, not winged, with 8-16 mostly solitary spikelets, occasionally paired at the base of the branches;
pedicels 0.2-1 mm, variously hirsute below, apices with fewer than 10 hairs more than 0.5 mm long.
3.8-5(6) mm long, 1.1-1.4 mm wide, lanceolate to ovate.
(3.1)3.5-4.5(5) mm long, 1.2-1.7 mm wide, lanceolate.
absent;
upper glumes equaling the lower lemmas, lanceolate to ovate, hairy, 5(7)-veined, acuminate to acute, unawned or awned, awns to 1.2 mm;
lower lemmas 3.6-5 mm long, 1.1-1.4 mm wide, lanceolate to ovate, setose, 5(7)-veined, acuminate to acute, unawned;
lower paleas absent;
anthers absent;
upper lemmas 2.3-3.3 mm, 0.7-0.9 times as long as the lower lemmas, indurate, elliptic, rounded, 5-veined, awned, the awns 0.1-0.3 mm;
upper paleas indurate, blunt, rugose.
as long as the lower lemmas, with sparsely appressed pubescence on the lower 2/3, scabrous or glabrous distally, 3-9-veined, acuminate and awned, awns 0.4-1 mm;
lower florets sterile;
lower lemmas 3-4.3 mm long, 1.2-1.7 mm wide, lanceolate, setose, 3-7-veined, acuminate, unawned or mucronate;
lower paleas absent;
upper lemmas 2-2.5 mm, indurate, elliptic, 5-7-veined, acute to rounded and awned, awns 0.4-1.1 mm;
upper paleas indurate, faintly rugose, blunt.
= 36.
= 36.
Eriochloa acuminata
Eriochloa contracta
Eriochloa acuminata is native to the southern United States and northern Mexico, but has become established outside this region. It may hybridize with E. lemmonii, from which it differs in its lack of lower paleas, upper glumes and lower lemmas with level veins, and narrower, glabrous or sparsely pubescent leaf blades.
There are two varieties of Eriochloa acuminata, differing as shown in the key below. Both grow in Mexico as well as the United States.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Eriochloa contracta grows in fields, ditches, and other disturbed areas. It is known only from the United States, being native and common in the central United States, and adventive to the east and southwest. It differs from E. acuminata in its tightly contracted, almost cylindrical panicles and longer lemma awns, but intermediate forms can be found. It can also be confused with first-year plants of the perennial E. punctata, which have glabrous leaves, narrower and more tapering spikelets, and longer lemma awns.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Spikelets 4-6 mm long, long-acuminate or tapering to a short awn | var. acuminata |
1. Spikelets 3.8-4 mm long, acute | var. minor |
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