Elymus multisetus
Elymus interruptus
big squirreltail, big squirreltail grass
Southwestern wildrye
15-65 cm, erect to ascending, usually puberulent;
nodes 4-6, mostly concealed, glabrous.
usually (40)60-100(120) cm, erect or the bases somewhat decumbent;
nodes 4-8, usually exposed, glabrous.
evenly distributed;
sheaths glabrous or white-villous;
auricles usually present, 0.5-1.5 mm;
ligules to 1 mm, truncate, entire or lacerate;
blades 1.5-4(5) mm wide, often ascending and involute, adaxial surfaces scabrous, pilose, or villous.
evenly distributed;
sheaths usually glabrous, occasionally hirsute;
auricles 0-2 mm, pale or reddish brown;
ligules to 1 mm;
blades 3-9 mm wide, lax, pale green, adaxial surfaces densely short-pilose, hispidulous, or scabridulous, especially on the veins.
5-20 cm long, 5-15 cm wide, erect, sometimes partially enclosed at the base, with 2 spikelets per node, rarely with 3-4 at some nodes;
internodes 3-5(8) mm long, 0.1-0.3 mm thick at the thinnest sections, glabrous beneath the spikelets.
5-20 cm long, 2-5 cm wide, erect to slightly nodding, with 2 spikelets per node;
internodes (5)8-14 mm long, 0.2-0.3 mm thick at the thinnest sections, without pronounced dorsal angles, often with green lateral bands, glabrous beneath the spikelets.
10-15 mm, divergent, with 2-4 florets, lowest florets sterile and glumelike in 1 or both spikelets at each node;
disarticulation initially at the rachis nodes, subsequently beneath each floret.
(6)9-15(22) mm, somewhat to strongly divergent, with 2-5 florets, lowest florets functional;
disarticulation above the glumes and beneath each floret.
subequal, (10)30-100 mm including the awns, the bases indurate and glabrous, glume bodies (2)5-10 mm long, 1-2 mm wide, setaceous, 2-3-veined, margins firm, awns (8)25-90 mm, each split into 3-9 unequal divisions, scabrous, flexuous to outcurving from near the glume bases at maturity;
fertile lemmas 8-10 mm, smooth or scabrous near the apices, 2 lateral veins extending into bristles to 10 mm, awns (10)20-110 mm long, about 0.2 mm wide at the base, divergent to arcuate;
paleas 7-9 mm, veins usually extending into about 1 mm bristles, apices acute to truncate;
anthers 1-2 mm.
subequal, 15-30 mm including the weakly differentiated awns, the basal 0-1 mm subterete and indurate, glume bodies, when distinguishable, about 6-10 mm long, (0.2)0.3-0.5(0.7) mm wide, linear-setiform to setaceous, entire, widening or parallel-sided above the base, 1-3-veined, glabrous or scabridulous, margins firm, awns straight or flexuous;
lemmas 7-10 mm, smooth or scabridulous, occasionally hirtellous especially near the margins, awns 15-22 mm, straight to moderately outcurving;
paleas 6-9 mm, obtuse or narrowly truncate, sometimes emarginate;
anthers 2-4.5 mm.
from late May to June.
May to July.
= 28.
= 28.
Elymus multisetus
Elymus interruptus
Elymus multisetus grows in dry, often rocky, open woods and thickets on slopes and plains, from central Washington and Idaho to southern California, Colorado, and northwestern Arizona, and from sea level to 2000 m. It has also been reported from Baja California, Mexico. It usually grows in less arid habitats than E. elymoides subsp. elymoides (p. 319), but the two taxa are sometimes sympatric.
Wilson (1963) reported a wide belt of introgression between Elymus multisetus and E. elymoides subsp. elymoides from southeastern California to southern Nevada, but not in other areas where they are sympatric. There are also probable hybrids with E. glaucus (p. 306) and Pseudoroegneria spicata (p. 281).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Elymus interruptus grows in dry to moist, rocky soil, often in canyons, open woods, and thickets, in the southwestern United States and northern Mexico. Apparent intermediates between E. interruptus and E. canadensis (p. 303) have been collected north of the documented range of typical E. interruptus in Arizona, New Mexico, and Iowa. Plants in the Ozark and Ouachita mountains, especially in Arkansas, that were previously referred to E. interruptus are now included in E. churchii (p. 314).
Elymus interruptus is a poorly understood southern species that, at one extreme, used to be included in E. canadensis or, at the other extreme, used to include E. churchii, E. svensonii (p. 314), and E. diversiglumis (p. 316), three species that seem more closely allied to E. hystrix (p. 316). Campbell (2002) suggested E. interruptus may have arisen from the introgression of E. hystrix or a related species into E. canadensis var. brachystachys. Artificial crosses between E. hystrix and E. canadensis were generally unsuccessful, but yielded some plants resembling E. interruptus (Church 1954). Elymus interruptus has been crossed with E. canadensis, E. hystrix, E. svensonii, E. virginicus (p. 298), E. glabriflorus (p. 296) and E. diversiglumis; only the hybrids with E. diversiglumis were completely sterile (Church 1954, 1967a; Brown and Pratt 1960).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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