Elymus wiegandii
Elymus ×ebingeri
northern riverbank wildrye, Wiegand's wild-rye, élyme de Wiegand
wildrye
100-180(220) cm, erect;
nodes 9-16, mostly concealed by the leaf sheaths, glabrous.
50-135 cm, usually smooth, glabrous, sometimes retrorsely hairy;
nodes glabrous or hairy.
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 smooth or scabridulous, hairy;
ligules to 1 mm;
blades 14-26 cm long, to 12 mm wide, flat, both surfaces scabridulous, adaxial surfaces hairy.
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.
8-17 cm, with (1)2+ spikelets per node;
internodes 4-8 mm.
12-20 mm, divergent, with (3)4-6(7) florets, lowest florets functional;
disarticulation above the glumes and beneath each floret.
diverging at about 45° from the rachises, not patent.
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.
usually subequal, 15-20 mm, bases indurate, bodies lanceolate to subulate, scabrous, sometimes the lower glumes reduced to a stub;
lemmas 8-10 mm, glabrous or strigose, sometimes scabrous, awns 23-29 mm, straight, scabrous;
anthers 2-2.9 mm.
seldom formed.
from mid-July to early August.
= 28.
Elymus wiegandii
Elymus ×ebingeri
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 ×ebingeri is the name for hybrids between E. virginicus (p. 298) and E. hystrix (p. 316). It is frequently found where the two parental species grow together, often with later hybrid generations and introgressants to the two parents. It has been reported from southern Ontario, and from Wisconsin to New York and Illinois. Most published reports simply refer to the existence of these hybrids, the name itself not having been published until 1996.
Elymus ×ebingeri is an Elymus named hybrid
Elymus is notorious for its ability to hybridize. Most of its interspecific hybrids are partially fertile, permitting introgression between the parents. The descriptions provided below are restricted to the named interspecific hybrids. They should be treated with caution and some skepticism; some are based solely on the type specimen, because little other reliably identified material was available. Moreover, as the descriptions of the non-hybrid species indicate, many other interspecific hybrids exist.
The parentage of all hybrids is best determined in the field. Perennial hybrids, such as those in Elymus, can persist in an area after one or both parents have died out, but the simplest assumption is that both are present. Interspecific hybrids of Elymus that have disarticulating rachises presumably have E. elymoides or E. multisetus as one of their parents.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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