Elymus wiegandii
Elymus ×palmerensis
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.
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.
(2)4-8(15) mm wide, abaxial surfaces scabrous, adaxial surfaces pilose.
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.
14-30 cm long, 1-2.5 cm wide including the awns, 0.3-0.8(1.5) cm wide excluding the awns, drooping, with 1-2 spikelets per node;
internodes 5-20 mm, scabrous on the angles.
12-20 mm, divergent, with (3)4-6(7) florets, lowest florets functional;
disarticulation above the glumes and beneath each floret.
with 3-9 florets.
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.
4-10.5 mm long, 0.8-1.5 mm wide, oblong to lanceolate, scabrous, gradually or abruptly narrowing in the distal 1/3-1/4, 3(4)-veined, margins scarious, apices unawned or awned, awns to 15 mm;
rachillas hairy;
lemmas 8.5-15 mm, hairy, conspicuously keeled distally, awned, awns 3-10 mm;
paleas 8.5-15 mm, retuse or truncate;
anthers 1-2 mm.
from mid-July to early August.
= 28.
Elymus wiegandii
Elymus ×palmerensis
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 ×palmerensis is the name for hybrids between E. macrourus (p. 324) and E. sibiricus (p. 310). It is known from disturbed sites around Palmer, Alaska, and in south-central Alaska. Bowden (1967) also reported it from Fort Liard, in the MacKenzie District, Northwest Territories. Lepage (1952) originally identified the parents as Agropyron sericeum [= E. macrourus] and E. canadensis (p. 303). Later, Lepage (1965) stated that the second parent was E. sibiricus. The above description includes ×Agroelymus hodgsonii Lepage, which, according to Bowden (1967), is a synonym.
Elymus ×palmerensis 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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