Elymus wiegandii
Elymus svensonii
northern riverbank wildrye, Wiegand's wild-rye, élyme de Wiegand
svenson's wildrye, Syenson's wildrye
100-180(220) cm, erect;
nodes 9-16, mostly concealed by the leaf sheaths, glabrous.
50-110 cm, erect;
nodes 6-8, mostly exposed, often reddish brown, 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 glabrous or villous, often somewhat purplish;
auricles 1-2 mm, purplish or reddish brown;
ligules to 1 mm, often reddish brown;
blades 4-8(10) mm wide, lax, usually pale green, adaxial surfaces usually villous.
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.
10-16 cm long, 3-5 cm wide, nodding, with 2 spikelets per node;
internodes (4)6-10(12) mm long, about 0.2 mm thick at the thinnest sections, flexuous, glabrous, without green lateral bands.
12-20 mm, divergent, with (3)4-6(7) florets, lowest florets functional;
disarticulation above the glumes and beneath each floret.
10-16 mm, usually appressed, with (3)4-5 florets, lowest florets functional;
disarticulation above the glumes, 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.
usually differing in length by more than 5 mm, sometimes vestigial to absent from the upper spikelets or throughout, (0)1-15(18) mm long including the undifferentiated awns, indurate at the base, 0.1-0.3 mm wide, setaceous to subulate, entire, 0-1-veined, tapering from the base, glabrous, margins firm, awns often curving outward;
lemmas 8-10 mm, glabrous, veins occasionally hispidulous near the lemma apices, awns (8)10-20(25) mm, moderately to strongly outcurving at maturity;
paleas 7-9 mm, obtuse or truncate, occasionally emarginate;
anthers 3-5 mm.
from mid-July to early August.
from mid-June to early July.
= 28.
= unknown.
Elymus wiegandii
Elymus svensonii
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 svensonii grows in dry, rocky soils in open woods of the interior low plateaus, mostly along bluffs of the Kentucky River and its tributaries in the bluegrass region of Kentucky, and along bluffs of the Cumberland River and its Caney Fork in the central basin of Tennessee. Most sites are on Ordovician limestone, but its discovery by Natural Heritage programs in Kentucky along the Green River on Mississippian limestone, and in Tennessee along the Piney River on Silurian limestone, suggest that it may be more widespread. It has been a candidate for federal protection in the United States.
Elymus svensonii, like E. diversiglumis (p. 316) and E. cburchii (see next), may be derived from hybrids between E. hystrix (p. 316) and E. canadensis (p. 303) (Church 1967a), even though E. canadensis currently has its eastern limit 50-100 miles west of most E. svensonii.
Elymus svensonii hybridizes naturally with E. hystrix, E. virginicus (p. 298) and other species of Elymus. Plants with little glume development are frequent; they appear to be introgressed by E. hystrix. Artificial crosses with E. interruptus (p. 306) have been successful, but those with E. diversiglumis have not (Church 1967a). Elymus svensonii resembles E. churchii; it differs in having less open spikes, shorter awns, more florets per spikelet, and more pubescent, glaucous foliage.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Go Botany
MI Flora
MN Wildflowers
WildflowerSearch
iNaturalist
USDA Plants Database
MO Plants
