Elymus wiegandii
Elymus interruptus
northern riverbank wildrye, Wiegand's wild-rye, élyme de Wiegand
Southwestern wildrye
100-180(220) cm, erect;
nodes 9-16, mostly concealed by the leaf sheaths, glabrous.
usually (40)60-100(120) cm, erect or the bases somewhat decumbent;
nodes 4-8, usually exposed, glabrous.
evenly distributed;
sheaths usually glabrous, occasionally villous, often reddish brown;
auricles 1-3 mm, brown;
ligules to 1 mm;
blades (8)10-20(24) mm wide, flat, lax, dark green, adaxial surfaces usually thinly pilose, with weakly spreading hairs on the veins at least near the margins, sometimes villous or glabrous.
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.
10-30 cm long, 3-5 cm wide, pendent, the bases often barely exserted, with 2 spikelets per node;
internodes 5-8(12) mm long, 0.2-0.3 mm thick at the thinnest sections, usually pubescent 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.
12-20 mm, divergent, with (3)4-6(7) florets, lowest florets functional;
disarticulation above the glumes and 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.
equal or subequal, 12-30 mm including the often undifferentiated awns, the basal 0.5-1 mm subterete and slightly indurate, glume bodies 7-12 mm long, (0.2)0.4-0.9(1.1) mm wide, linear-setiform, entire, widening or parallel-sided above the base, 1-3(5)-veined, glabrous, hispidulous or villous, especially near the margins, margins firm, awns (5)8-15(18) mm, straight or flexuous;
lemmas 10-15 mm, usually uniformly appressed-villous, rarely scabrous-hirtellous or glabrous, awns 15-25(30) mm, moderately to strongly outcurving;
paleas 9-14 mm, narrowly truncate, minutely bidentate;
anthers 2-3.5 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 mid-July to early August.
May to July.
= 28.
= 28.
Elymus wiegandii
Elymus interruptus
Elymus wiegandii grows in moist or damp, rich, alluvial soil, especially on sandy river terraces and in woods and thickets, primarily from Saskatchewan through much of the Great Lakes region to Nova Scotia and Connecticut. It has abnormal neocentric chromosomes with meiotic irregularities that appear to limit the fertility of its hybrids, and even some crosses within the species (Vilkomerson 1950). It may be derived from hybrids between E. canadensis (p. 303) and perhaps E. riparius (p. 302). The latter species is similar to E. wiegandii and overlaps with it in range and habitat within the Great Lakes region, where there are a few plants that appear to be hybrids between the two. Plants with scabrous-hirtellous or glabrous lemmas (E. wiegandii f. calvescens Fernald) are known from Maine and New Hampshire.
Elymus wiegandii is often confused with sympatric E. canadensis and E. diversiglumis (p. 316), but it has a distinctive robust, broad-leaved habit. It is intermediate between the two in spike density and glume development. Occasional plants with glabrous leaves and less pendent spikes suggest introgression from E. canadensis, but artificial crosses produced no fertile Fj plants (Church 1958).
(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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