Flora of North America species comparison

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Elymus scribneri

Elymus ×hansenii

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

Hansen squirreltail, Hansen's wheatgrass, Hansen's wildrye
Habit Plants cespitose, not rhizomatous. Plants cespitose, not rhizomatous.
Culms

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

nodes glabrous.

60-120 cm.
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

evenly distributed;

sheaths smooth;

ligules to 1 mm;

blades 10-30 cm long, 2-8 mm wide, flat or the margins involute.
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.

5-20 cm, straight or nodding, with 2+ spikelets per node;

internodes about 10 mm;

disarticulation in the rachises.
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.

about 15 mm, with 3-5 florets.
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.

narrowly lanceolate, 2-3-veined, awned, awns 25-35 mm;

lemmas 10-12 mm, awned, awns 40-50 mm, outcurving;

paleas subequal to the lemmas, truncate or bidentate.
2n

= 28.

Elymus scribneri

Elymus ×hansenii
Distribution
from FNA
AZ; CA; CO; ID; MT; NM; NV; OR; UT; WA; WY; AB
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; CO; ID; NV; OR; UT; WA; WY
[WildflowerSearch map]
[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.)

Elymus ×hansenii refers to hybrids between E. glaucus (p. 306) and either E. elymoides or E. multisetus (p. 318). It is not clear which of the latter two species is involved. It is a fairly common hybrid in those parts of western North America where both parents grow. The glumes of the type specimen are as wide as those in E. glaucus, and some are divided longitudinally, as in E. elymoides and E. multisetus. As in other hybrids involving E. elymoides and E. multisetus, the rachis of E. ×hansenii disarticulates at maturity.

Elymus ×hansenii 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. ×palmerensis, E. ×pinalenoensis, E. ×pseudorepens, E. ×saundersii, E. ×yukonensis
Synonyms Agropyron scribneri Sitanion hansenii
Name authority (Vasey) M. E. Jones Scribn.
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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