13.14 ×ELYLEYMUS B.R. Baum

Mary E. Barkworth

Plants perennial; sometimes rhizomatous. Culms 40–235 cm, erect. Inflorescences usually spikes, sometimes spikelike racemes, 5–35 cm, erect, with 1–3 spikelets per node, pedicels, when present, to 3 mm. Spikelets with 2–8 florets; disarticulation usually above the glumes and below the florets, sometimes below the glumes, sometimes in the rachises, usually tardy. Glumes linear to lanceolate, often awn-tipped; lemmas 6–25 mm, glabrous or hairy, usually awned, awns to 15 mm; anthers 1.5–5 mm.

×Elyleymus consists of hybrids between Elymus and Leymus. So far as is known, they are completely sterile, having thin anthers (usually less than 0.5 mm thick) and failing to develop mature caryopses. Only the named hybrids are accounted for below. Each of the entities appears to be distinct, but identification of the parents is, in some instances, tentative. The descriptions are offered with considerable reservation, some being based solely on the type material. All the illustrations are based on type specimens.

The hybrids fall into two groups. Those with Leymus mollis as the Leymus parent (species 7–11) tend to have wider and flatter glumes than those with one of the inland species of Leymus as the Leymus parent.

Unless stated otherwise, measurements of the spikes include the awns; measurements of the spikelets, glumes, and lemmas do not. No attempt has been made to develop distribution maps.

SELECTED REFERENCES Bowden, W.M. 1959. Chromosome numbers and taxonomic notes on northern grasses: I. Tribe Triticeae. Canad. J. Bot. 37:1143–1151; Bowden, W.M. 1967. Cytotaxonomy of intergeneric hybrids of the tribe Triticeae from North America. Canad. J. Bot. 45:711–724; Dewey, D.R. and A.H. Holmgren. 1962. Natural hybrids of Elymus cinereus and Sitanion hystrix. Bull. Torrey Bot. Club 89:217–228; Lepage, E. 1952. Études sur quelques plantes américaines: II. Hybrides intergénériques; Agrohordeum et Agroelymus. Naturaliste Canad. 79:241–266.

1. ×Elyleymus turneri (Lepage) Barkworth & D.R. Dewey

Plants not cespitose, rhizomatous. Culms 110–130 cm, pubescent below the spikes. Leaves glaucous; auricles present, at least on the innovations; blades 3–5 mm wide, abaxial surfaces scabrous or smooth, adaxial surfaces scabrous. Inflorescences spikelike racemes, 11–20 cm long, lax, with (1)2 spikelets per node, spikelets at the lower nodes unequally pedicellate, longer pedicels 1.5–3 mm; internodes 6–15(30) mm, those at the base of the spike longest, angles hispid, convex surfaces pubescent or pilose. Spikelets 15–25 mm, with 5–8 florets; disarticulation above or below the glumes. Glumes unequal, 2–17 mm long, 0.5–1.2 mm wide, subulate to narrowly lanceolate, scabrous or pilose, (0)1–3-veined; rachilla internodes pubescent; lemmas 6–16 mm, pubescent, pilose, or villous, backs often glabrate, apices awned, awns 0.7–8 mm; paleas 6.5–10 mm, puberulent or pubescent between the veins; anthers (2.8)3.5–5 mm. 2n = 28.

×Elyleymus turneri is treated here as the name for hybrids between Elymus lanceolatus and Leymus innovatus, in agreement with Bowden (1952). The type material was found on the banks of the Saskatchewan River, 2 miles below Fort Saskatchewan, Alberta. Lepage (1952) noted that Dr. Turner, the collector, reported that both Agropyon smithii [≡ Pascopyrum smithii] and A. dasystachyum [= Elymus lanceolatus] grew in the vicinity, and argued for Agropyron smithii as the Elymus parent. Bowden (1959) reported 2n = 28 in specimens from the type locality, and used this to argue for the Elymus parent being either A. dasystachyum [= Elymus lanceolatus] or A. trachycaulum [≡ Elymus trachycaulus].

2. ×Elyleymus aristatus (Merr.) Barkworth & D.R. Dewey

Plants not or shortly rhizomatous. Culms 60–130 cm, glabrous. Leaves evenly distributed on the culms; sheaths smooth, glabrous; auricles poorly developed, to 0.5 mm; ligules 1–2.5 mm, scarious, rounded; blades about 5.5 mm wide, abaxial surfaces glabrous, mostly smooth, scabrous near the margins, adaxial surfaces scabridulous, primary veins separated by about 3 secondary veins. Inflorescences spikes, 6–15 cm long, 10–15 mm wide including the awns, 7–10 mm wide excluding the awns, erect, with 2–3 sessile or subsessile spikelets per node; internodes 4–7 mm, concealed by the spikelets; disarticulation tardy, in the rachises and beneath the florets. Spikelets 10–15 mm excluding the awns, to 18 mm including the awns, with 3–4 florets. Glumes 8–15 mm long, 0.3–0.5 mm wide, subequal to unequal, scabrous; lemmas 7.5–9 mm, glabrous, mostly smooth, scabridulous distally, midveins prominent and scabrous distally, awns 4–5 mm; anthers 2.2–2.4 mm.

Dewey and Holmgren (1962) argued that ×Elyleymus aristatus comprises hybrids between Elymus elymoides and Leymus cinereus or L. triticoides. It has been found at many locations where the parents are sympatric.

3. ×Elyleymus colvillensis (Lepage) Barkworth

Plants loosely cespitose, shortly rhizomatous. Culms about 60 cm, glabrous. Auricles often present; ligules 0.3–1.2 mm, truncate; blades 2–4 mm wide, scabrous on the adaxial surfaces. Inflorescences spikes, 6.5–12 cm, somewhat lax, with 1(2) sessile or subsessile spikelets per node; internodes 4–9 mm, angles pilose or hispid, convex surfaces sparsely villous distally. Spikelets 10–15 mm, with 3–5 florets; disarticulation above the glumes, beneath the florets. Glumes 6.5–11.5 mm long, 1.1–1.5 mm wide, narrowly lanceolate to subulate, 1–3(4)-veined, margins narrow, scarious; lemmas 8–11 mm, villous, slightly to strongly keeled, awned, awns 2–10 mm; paleas glabrous or puberulent between the veins, apices slightly dentate or retuse; anthers 1.7–2.2 mm.

×Elyleymus colvillensis consists of hybrids between Leymus innovatus and, probably, Elymus alaskanus. The original collections were made on the banks of the Colville River at Umiat, Alaska. It is not known how widely it is distributed.

4. ×Elyleymus hirtiflorus (Hitchc.) Barkworth

Plants rhizomatous. Culms 40–90 cm tall, 2–2.5 mm thick, glabrous. Leaves somewhat basally concentrated; sheaths smooth, glabrous; auricles 0.3–0.5 mm; ligules 0.2–0.5 mm, truncate; blades 5–20 mm long, 2–4 mm wide, usually involute, sometimes flat, abaxial surfaces smooth, glabrous or sparsely hairy, particularly towards the base, veins not prominent, adaxial surfaces scabridulous or scabrous, varying within a plant, all veins equally prominent, apices narrowly acute. Inflorescences spikes, 5–18 cm long, 8–10 mm wide, with 1–2 sessile or subsessile spikelets per node; internodes 4–5 mm, partially exposed on the sides, hairy. Spikelets 11–14 mm, to 23 mm including the awns, with 3–6 florets; disarticulation above the glumes, beneath the florets. Glumes 12–17 mm long including the awnlike apices, 1–3 mm wide, widest at about 1/4 length, 1(3)-veined, keeled, sparsely to densely hairy, hairs 0.3–0.5 mm; lemmas 8.5–10 mm, sparsely to densely hairy, hairs 0.3–0.5 mm, apices awned, awns 5–10 mm, straight; anthers 1.8–2 mm long.

Bowden (1967) suggested that ×Elyleymus hirtiflorus consisted of hybrids between Elymus trachycaulus and Leymus innovatus, and included in it plants from British Columbia, Canada. The name, however, is based on collections from the banks of the Green River, Wyoming, where neither putative parent grows. The more likely parents are Elymus lanceolatus and Leymus simplex. Admittedly, the short anthers argue for E. trachycaulus rather than E. lanceolatus as the Elymus parent. The Canadian specimens are here treated as belonging to ×Elyleymus ontariensis, a name that Bowden treated as a synonym of ×Elyleymus hirtiflorus.

5. ×Elyleymus mossii (Lepage) Barkworth

Plants cespitose, sometimes rhizomatous. Culms to 80 cm, glabrous. Sheaths smooth, glabrous; auricles 0.5–1.5 mm; ligules 0.5–1.2 mm; blades 3–7 mm wide, flat, adaxial surfaces and margins scabrous. Inflorescences spikes, 8–15 cm long, 10–25 mm wide including the awns, 8–15 mm wide excluding the awns, with (1)2 sessile or subsessile spikelets per node; internodes 4–6 mm, scabrous or hispid on the angles. Spikelets 12–17 mm, usually with 5 florets. Glumes 9–15 mm long including the awns, 0.8–1 mm wide, 1–3-veined, hairy; lemmas 8–13 mm, villous, awned, awns 4–15 mm; paleas 8–10 mm, glabrous between the keels, margins shortly ciliate; anthers 2–3 mm.

Lepage (1965) stated that it was obvious that Elymus canadensis was one parent of this hybrid, but that it would be necessary to discover which species of Agropyron [in the traditional sense] grew in the neighborhood to determine the other parent. He gave “Agropyron (?) trachycaulum” as a possibility. Elymus canadensis, however, is generally absent from the region around Lake Louise, Alberta (Moss 1983), where the holotype was collected. Barkworth (2006) argued that the parents are probably E. glaucus and Leymus innovatus, both species that are common in the holotype area.

6. ×Elyleymus ontariensis (Lepage) Barkworth

Plants rhizomatous. Culms to 75 cm tall, 2–2.5 mm thick, clustered, glabrous. Leaves more or less evenly distributed; sheaths glabrous, smooth; auricles absent or to 0.3 mm; ligules about 0.5 mm, truncate; blades 10–25 cm long, 2–3 mm wide, involute, abaxial surfaces scabridulous, glabrous, veins not evident, adaxial surfaces smooth or scabridulous, glabrous, veins all equally prominent, apices narrowly acuminate. Inflorescences spikes, 8–12 cm long, 6–12 mm wide, with 1(2) sessile or subsessile spikelets per node; internodes 6–9 mm, partly exposed, angles hairy, hairs 0.4–0.6 mm; disarticulation above the glumes, beneath the florets. Spikelets 15–20 mm, with 3–5 florets. Glumes 9.5–16 mm long including the awns, 0.7–1.3 mm wide, lanceolate, widest about midlength, 3-veined, hairy or scabrous over the veins, awns 1–1.5 mm; lemmas 10–15 mm, hairy, hairs 0.3–0.4 mm, awns 3–7 mm; anthers about 2.8 mm.

×Elyleymus ontariensis, according to Bowden (1967), comprises hybrids between E. trachycaulus and Leymus innovatus. It differs from ×Elyleymus hirtiflorus in having wider, more parallel-sided glumes and longer rachis internodes.

7. ×Elyleymus uclueletensis (Bowden) B.R. Baum

Plants rhizomatous. Culms 170–235 cm tall, 4–5 mm thick, smooth, mostly glabrous, hairy for 12–15 cm below the spikes, hairs 0.1–0.2 mm. Leaves evenly distributed on the culms; sheaths smooth, glabrous: auricles absent; ligules 0.5–0.7 mm, truncate; blades 6–10 mm wide, smooth, glabrous, abaxial surfaces with the primary veins evident, adaxial surfaces with the primary and secondary veins evident. Inflorescences spikes, 25–35 cm long, about 15 mm thick, with 2 sessile or subsessile spikelets per node; internodes 7–14 mm. Spikelets 14–20 mm excluding the awns, to 25 mm with awns, with 2–3 florets; disarticulation above the glumes, beneath the florets. Glumes 12–25 mm long including the awns, 0.8–2 mm wide, widest near midlength, flexible, hairy, hairs about 0.4 mm, bases indurate for about 0.3 mm, 3–5 veins evident at midlength, margins about 0.5 mm wide, apices tapering into awns, awns 1–3 mm; lemmas 20–25 mm, hairy, hairs about 0.4 mm, awned, awns 2.5–9(11) mm; anthers 2.5–3.5 mm long.

×Elyleymus ucluetensis comprises hybrids between Leymus mollis and Elymus glaucus. It is known from two locations, near Ucluelet and along Gold River, both on the west coast of Vancouver Island, British Columbia.

8. ×Elyleymus aleuticus (Hultén) B.R. Baum

Plants Culms to 75 cm tall, most glabrous, hairy for about 1 cm below the spikes, hairs about 0.1 mm. Blades to 15 mm wide, adaxial surfaces with the primary and secondary veins evident, subequal. Inflorescences spikes, to 15 cm long, 20 mm wide, erect, with (1)2 subsessile spikelets per node, pedicels to 1 mm; internodes about 5 mm. Spikelets with 3–5 florets; disarticulation above the glumes, beneath the florets. Glumes 10.5–13 mm long, 1.3–2(2.3) mm wide, linear-lanceolate to linear, flexible, hairy, 3–4(5)-veined, veins prominent, apices unawned or awned, awns to 1.2 mm; lemmas 15–18 mm, lemmas awned, awns 1–7 mm, more or less straight; anthers 2.3–3.9 mm.

×Elyleums aleuticus comprises hybrids between Elymus hirsutus and Leymus mollis. It is known only from the type locality, Atka, Alaska. It probably occurs at other locations where the two parents are sympatric.

9. ×Elyleymus hultenii (Melderis) Barkworth

Plants cespitose, shortly rhizomatous. Culms to 60 cm, glabrous, hairy below the spikes, nodes shortly hairy. Sheaths smooth, glabrous; auricles absent or to 0.5 mm; ligules 0.2–0.8 mm, truncate; blades 3–4 mm wide, adaxial surfaces densely strigulose over the veins, all veins equally prominent. Inflorescences spikes, 9–17 cm long, 8–10 mm wide, erect, with solitary, sessile or subsessile spikelets. Spikelets 15–20 mm, with 4–6 florets. Glumes 9–11 mm long, 1.5–3 mm wide, with 4–5 veins, hairy, acute, unawned; lemmas 10–12 mm, hairy, unawned or awned, awns to about 1 mm; paleas with short and long hairs on the keels; anthers 3–4 mm.

×Elyleymus hultenii consists of hybrids between Elymus alaskanus subsp. alaskanus and Leymus mollis. The original collection is from Deering, Alaska.

10. ×Elyleymus jamesensis (Lepage) Barkworth

Plants rhizomatous. Culms 90–130 cm tall, about 5 mm thick. Leaves somewhat basally concentrated; sheaths smooth, glabrous; auricles well developed; ligules about 0.3 mm on the lower leaves, to 3 mm on the upper leaves; blades 5–6 mm wide, veins equally prominent on the adaxial surfaces. Inflorescences spikes, 15–25 cm long, 6–12 mm wide, with 1–2 sessile or subsessile spikelets per node; internodes 8–15 mm, angles scabrous or hispid. Spikelets 16–28 mm, with 3–4(5) florets. Glumes 12–20 mm long, 2–3 mm wide, 3–5-veined, scabrous and sparsely hairy, tapering gradually from about midlength, margins scarious, apices subulate or awned, awns to 4 mm; rachilla internodes pubescent or villous; lemmas 8.7–16 mm, with appressed hairs at the base, glabrous elsewhere, awned, awns 1–3 mm; paleas with ciliate keels and retuse to bidentate apices; anthers 2–3 mm.

×Elyleymus jamesensis comprises hybrids between Elymus trachycaulus and Leymus mollis. Lepage (1952) recognized three different infraspecific taxa, depending on the variety of Agropyron trachycaulum [≡ Elymus trachycaulus] involved. Because all the varieties concerned are treated here as part of E. trachycaulus subsp. trachycaulus, no attempt has been made to distinguish Lepage’s infraspecific taxa. The above description includes ×Agroelymus adamsii J. Rousseau, which, according to Bowden (1967), is a synonym of ×E. jamesensis.

11. ×Elyleymus ungavensis (Louis-Marie) Barkworth

Plants rhizomatous. Culms to about 100 cm tall, 3–5 mm thick, glabrous, lower internodes glaucous. Leaves somewhat basally concentrated; sheaths smooth, glabrous; auricles present on some basal leaves, to 0.4 mm; ligules about 0.5 mm, truncate; blades of the culms 5–7 mm wide, abaxial surfaces smooth, glabrous, primary and secondary veins evident, adaxial surfaces scabrous, glabrous, all veins more or less equally prominent, blades of the innovations to 3 mm wide. Inflorescences spikes, to 18 cm long, about 10 mm wide, with 1 sessile or subsessile spikelet per node; internodes 7–9 mm, mostly glabrous, angles hairy, hairs about 0.3 mm. Spikelets 15–25 mm, with 5–7 florets; disarticulation above the glumes, beneath the florets. Glumes 15–20 mm long including the awnlike tip, 2.5–4 mm wide, widest at or just beyond midlength, purplish, sparsely scabrous to hairy over the veins, margins about 1 mm wide, apices acuminate, unawned; lemmas 15–17 mm, evenly hairy, hairs 0.4–0.5 mm, apices mucronate, mucros about 0.5 mm; anthers about 1.8 mm long.

×Elyleymus ungavensis is a northern hybrid, collected along the sandy banks of the Koksoak River, near Fort Chimo [= Kuujjuaq], at the southern end of Ungava Bay, Quebec. It consists of hybrids between Elymus violaceus and Leymus mollis subsp. mollis. The involvement of E. violaceus is suggested by the wide glume margins, that of L. mollis subsp. mollis by the relatively thick culms.