Flora of North America species comparison

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Elymus scribneri

Elymus ×yukonensis

Scribner's wheat grass, Scribner's wild rye, spreading wheatgrass

Yukon wheatgrass
Habit Plants cespitose, not rhizomatous. Plants rhizomatous.
Culms

15-35(55) cm, prostrate to strongly decumbent, at least at the base;

nodes glabrous.

about 60 cm, erect.
Sheaths

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.

Leaves

somewhat basally concentrated;

blades 3.5-6 mm wide.
Spikes

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.

6-10 cm long, 0.7-1.7 cm wide, with 1 spikelet per node;

internodes 6-11 mm.
Spikelets

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.

Glumes

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.

4-5.5 mm, about 1/2 the length of the adjacent lemmas, lanceolate, flat, hairy, apices acute or awn-tipped, awns shorter than 1 mm;

rachillas densely hairy;

lemmas 6-9 mm, densely villous, unawned;

anthers 3.3-3.6 mm.
2n

= 28.

Elymus scribneri

Elymus ×yukonensis
Distribution
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; BC
[BONAP county map]
Discussion

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.)

The parents of Elymus ×yukonensis have not been identified. Morphological and geographic considerations suggest that they may be E. lanceolatus subsp. psammophilus (p. 327) and E. alaskanus (p. 326).

Elymus ×yukonensis 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.)
Source FNA vol. 24, p. 330. FNA vol. 24, p. 340.
Parent taxa Poaceae > subfam. Pooideae > tribe Triticeae > Elymus Poaceae > subfam. Pooideae > tribe Triticeae > Elymus
Sibling taxa
E. alaskanus, E. albicans, E. arizonicus, E. bakeri, E. canadensis, E. caninus, E. churchii, E. ciliaris, E. curvatus, E. dahuricus, E. diversiglumis, E. elymoides, E. glabriflorus, E. glaucus, E. hirsutus, E. hoffmannii, E. hystrix, E. interruptus, E. lanceolatus, E. macgregorii, E. macrourus, E. multisetus, E. pringlei, E. repens, E. riparius, E. semicostatus, E. sibiricus, E. sierrae, E. stebbinsii, E. svensonii, E. texensis, E. trachycaulus, E. tsukushiensis, E. villosus, E. violaceus, E. virginicus, E. wawawaiensis, E. wiegandii, E. ×cayouetteorum, E. ×ebingeri, E. ×hansenii, E. ×palmerensis, E. ×pinalenoensis, E. ×pseudorepens, E. ×saundersii, E. ×yukonensis
E. alaskanus, E. albicans, E. arizonicus, E. bakeri, E. canadensis, E. caninus, E. churchii, E. ciliaris, E. curvatus, E. dahuricus, E. diversiglumis, E. elymoides, E. glabriflorus, E. glaucus, E. hirsutus, E. hoffmannii, E. hystrix, E. interruptus, E. lanceolatus, E. macgregorii, E. macrourus, E. multisetus, E. pringlei, E. repens, E. riparius, E. scribneri, E. semicostatus, E. sibiricus, E. sierrae, E. stebbinsii, E. svensonii, E. texensis, E. trachycaulus, E. tsukushiensis, E. villosus, E. violaceus, E. virginicus, E. wawawaiensis, E. wiegandii, E. ×cayouetteorum, E. ×ebingeri, E. ×hansenii, E. ×palmerensis, E. ×pinalenoensis, E. ×pseudorepens, E. ×saundersii
Synonyms Agropyron scribneri Agropyron yukonense
Name authority (Vasey) M. E. Jones (Scribn. & Merr.) Á. Löve
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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