Elymus scribneri
Elymus ×cayouetteorum
Scribner's wheat grass, Scribner's wild rye, spreading wheatgrass
wildrye
15-35(55) cm, prostrate to strongly decumbent, at least at the base;
nodes glabrous.
to 1 m tall, about 4 mm thick.
glabrous or shortly pilose;
auricles usually present, 0.5-1 mm;
ligules 0.2-0.4(0.7) mm, usually truncate, occasionally acute, entire to erose;
blades 1.5-4 mm wide, usually involute, adaxial surfaces prominently ribbed.
not basally concentrated;
sheaths smooth;
ligules about 0.5 mm, glabrous;
blades 20-30 cm long, about 10 mm wide, both surfaces scabrous.
3.5-10 cm long, 0.8-1.2 cm wide excluding the awns, 3-6 cm wide including the awns, usually with 1 spikelet per node, occasionally with 2 spikelets at the lower nodes;
internodes 2.5-5(7) mm long, 0.5-1 mm wide, glabrous, mostly smooth, edges scabrous.
about 25 cm, lower nodes with 1 spikelet, most middle to upper nodes with 2;
internodes about 18 mm.
9-15 mm long, 6-12 mm wide, appressed to ascending, with 3-6 florets;
rachilla internodes 0.8-1.3 mm, scabridulous;
disarticulation initially at the rachis nodes, subsequently beneath each floret.
about 40 mm including the awns, about 20 mm excluding the awns, appressed, with 5-8 florets.
4-9 mm long, 0.5-1 mm wide, mostly glabrous, midveins scabrous, 3-5-veined, entire, tapering into a divergent, 12-30 mm awn;
lemmas 7-10 mm, usually glabrous, occasionally scabridulous, awned, awns 15-30 mm, divergent, scabridulous;
paleas usually longer than the lemmas, apices ciliate, truncate or the veins extending into teeth, teeth about 0.5 mm;
anthers 1-1.6 mm.
12-15 mm, not or scarcely indurate, mostly smooth, veins scabrous, awns 3-5 mm;
lemmas about 14 mm, glabrous, awns 18-22 mm, not to moderately divergent;
anthers 1.8-2 mm, indehiscent.
= 28.
Elymus scribneri
Elymus ×cayouetteorum
Elymus scribneri grows in rocky areas in open subalpine and alpine regions, at 2500-3200 m, often in windswept locations, in southwestern Alberta and the western United States. It is often confused with E. elymoides (p. 318), but differs from that species in having only one spikelet per node, wider glumes, and more tardily disarticulating rachises. It also resembles E. sierrae (see next), from which it differs in its disarticulating rachises, denser spikes, and shorter anthers.
Dewey (1963) concluded that Elymus trachycaulus subsp. andinus consists of hybrids between E. scribneri and E. trachycaulus (p. 321). In addition, several taxonomists have suggested that E. scribneri consists of fertile hybrids between E. violaceus (p. 324) and E. elymoides. This suggestion is supported by the frequency with which the three taxa are sympatric, the morphological variation exhibited by E. scribneri, and cytogenetic data (Dewey 1967).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Elymus ×cayouetteorum consists of hybrids between E. trachycaulus (p. 321) and E. canadensis (p. 303). The above description is based on the type specimen, which was collected on the Ilets Jeremie, Quebec. It is not known how widespread such hybrids are.
Elymus ×cayouetteorum 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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