Elymus macgregorii
Elymus svensonii
early wild-rye
svenson's wildrye, Syenson's wildrye
40-120 cm, erect or slightly decumbent;
nodes 4-8, mostly exposed, glabrous.
50-110 cm, erect;
nodes 6-8, mostly exposed, often reddish brown, glabrous.
evenly distributed;
sheaths usually glabrous, rarely villous;
auricles 2-3 mm, usually purplish black when fresh, sometimes light brown;
ligules shorter than 1 mm;
blades 7-15 mm wide, lax, dark glossy green under the glaucous bloom, adaxial surfaces usually glabrous, occasionally villous.
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.
4-12 cm long, (1.7)2.2-3(4)4 cm wide, erect, exserted, with (6)9-16(20) nodes and 2 spikelets at all or most nodes, sometimes with 3 at some nodes;
internodes 4-7 mm long, about 0.3 mm thick and 2-angled at the thinnest sections, usually glabrous or scabridulous 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.
10-15 mm, strongly divergent, glaucous, maturing to pale yellowish brown, with (2)3-4 florets, lowest florets functional;
disarticulation below the glumes and each floret, the lowest floret often falling with the glumes.
10-16 mm, usually appressed, with (3)4-5 florets, lowest florets functional;
disarticulation above the glumes, beneath each floret.
subequal, entire, the basal 1-3 mm terete or subterete, indurate, without evident venation, moderately bowed out, glume bodies 8-16 mm long, 1-1.8 mm wide, linear-lanceolate, widening or parallel-sided above the base, (2)4-5(8)-veined, usually glabrous, occasionally hirsute, sometimes scabrous, margins firm, awns (10)15-20(25) mm, straight except the awns of the lowest spikelets occasionally contorted;
lemmas 6-12 mm, usually glabrous, sometimes scabrous, occasionally villous, awns (15)20-30 mm, straight;
paleas 6-10 mm, apices obtuse;
anthers 2-4 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.
usually mid-May to mid-June.
from mid-June to early July.
= 28.
= unknown.
Elymus macgregorii
Elymus svensonii
Elymus macgregorii grows in moist, deep, alluvial or residual, calcareous or other base-rich soils in woods and thickets, mostly east of the 100th Meridian in the contiguous United States. It used to be confused with E. glabriflorus (p. 296) or E. virginicus (p. 298), but it reaches anthesis about a month earlier than sympatric populations of these species. In most of its range, E. macgregorii has purplish black auricles; light brown auricles may be locally abundant, particularly in populations at the limits of its range.
Elymus macregorii hybridizes with several species, but especially E. virginicus and E. hystrix (p. 316) (Campbell 2000). Western plants often have smaller, more condensed spikes and distinctly villous leaves, suggesting a transition to E. virginicus var. jejunus (p. 300). Transitions to E. virginicus var. jejunus can also be recognized to the north, where the dates of anthesis are delayed, but even in Maine, E. macgregorii reaches anthesis about 10 days earlier than E. virginicus (Campbell and Haines 2002). Plants with villous lemmas grow at scattered locations; they have not been reported in distinct habitats, nor in large enough populations to warrant taxonomic recognition.
(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.)
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