Elymus lanceolatus
Elymus ×hansenii
streambank wheatgrass, streamside wild rye, thick-spike wildrye, thickspike wheatgrass
Hansen squirreltail, Hansen's wheatgrass, Hansen's wildrye
22-130 cm, erect;
nodes glabrous.
60-120 cm.
often mostly basal, sometimes more evenly distributed;
sheaths glabrous or pubescent;
auricles usually present on the lower leaves, 0.5-1.5 mm;
ligules 0.1-0.5 mm, erose, sometimes ciliolate;
blades 1.5-6 mm wide, generally involute, abaxial surfaces usually glabrous, adaxial surfaces strigose, ribs subequal in size and spacing.
evenly distributed;
sheaths smooth;
ligules to 1 mm;
blades 10-30 cm long, 2-8 mm wide, flat or the margins involute.
3.5-26 cm long, 0.5-1 cm wide, erect to slightly nodding, usually with 1 spikelet per node, sometimes with 2 at a few nodes;
internodes 3.5-15 mm long, 0.1-0.8 mm wide, glabrous or hairy.
5-20 cm, straight or nodding, with 2+ spikelets per node;
internodes about 10 mm;
disarticulation in the rachises.
8-31 mm, 1.5-3 times longer than the internodes, appressed, with 3-11 florets;
rachillas glabrous or hairy, hairs to 1 mm;
disarticulation above the glumes, beneath each floret.
about 15 mm, with 3-5 florets.
subequal, 5-14 mm long, 1/2 - 3/4 the length of the adjacent lemmas, 0.7-1.3 mm wide, lanceolate, glabrous or hairy, smooth or scabrous, 3-5-veined, flat or weakly, often asymmetrically keeled, keels straight, margins narrow, tapering from the base or from beyond midlength, apices acute to acuminate, sometimes mucronate or shortly awned;
lemmas 7-12 mm, glabrous or hairy, hairs all alike, sometimes scabrous, acute to awn-tipped, awns to 2 mm, straight;
paleas about equal to the lemmas, keels straight below the apices, smooth or scabrous proximally, sometimes hairy, scabrous distally, intercostal region glabrous or with hairs, apices 0.2-0.3 mm wide;
anthers (2.5)3-6 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.
= 28.
Elymus lanceolatus
Elymus ×hansenii
Elymus lanceolatus grows in sand and clay soils and dry to mesic habitats. It is found primarily in the western half of the Flora region, between the coastal mountains and 95° W longitude, with the exception of E. lanceolatus subsp. psammophilus, which extends around the Great Lakes. Three subspecies are recognized, primarily on the basis of their lemma and palea pubescence.
Elymus lanceolatus is primarily outcrossing, and hybridizes with several species of Triticeae. Elymus albicans (p. 334) is thought to be derived from hybridization with the awned phase of Pseudoroegneria spicata (p. 281). Judging from specimens of controlled hybrids, hybridization with E. trachycaulus (p. 321) and unawned plants of P. spicata probably occur, but would be almost impossible to detect without careful observation in the field. Experimental hybrids are partially fertile, and capable of backcrossing to either parent (Dewey 1965, 1967, 1968, 1975, 1976).
(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.)
1. Lemmas densely hairy, hairs flexible, some 1 mm long or longer | subsp. psammophilus |
1. Lemmas glabrous or with stiff hairs shorter than 1 mm. | → 2 |
2. Lemmas with hairs, not scabrous | subsp. lanceolatus |
2. Lemmas smooth, sometimes scabrous distally, mosdy glabrous, sometimes the lemma margins hairy proximally | subsp. riparius |
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