OregonFlora: Elymus macgregorii vs. Elymus repens

	Elymus macgregorii	Elymus repens
		quackgrass
Habit		Plants perennial, 50–100 cm tall, strongly rhizomatous, sometimes glaucous.
Culms		erect to geniculate.
Leaves		sheaths with spreading hairs or glabrous proximally; blades 6–10 mm wide, usually flat; lower surfaces glabrous or sparsely pilose; upper surfaces usually with sparse spreading hairs over the veins but sometimes glabrous.
Inflorescences		5–15 cm, 1 spikelet per node but occasionally with 2 at a few nodes; internodes 4–6(9.5)mm; disarticulation above the glumes; beneath each floret.
Spikelets		10–27 mm, appressed to ascending, 4–7 florets.
Glumes		oblong, glabrous; the midveins scabrous and keeled near the tip but smooth and relatively flat near the base; hyaline margins present in the distal half; tips acute to acuminate; awnless or awned; to 3 mm; lower glumes 8.8–11.4 mm, 3–6-veined; upper glumes 7–12 mm, 5–7-veined.
Lemmas		8–12 mm, glabrous, mostly smooth but sometimes minutely scabrous distally; awnless or awned; lemma awns 0–4(10)mm; straight.
Anthers		4–7 mm.
2n		=22, 42.

	Elymus macgregorii	Elymus repens
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion		Disturbed areas, roadsides, ditches, streamsides. 0–2400m. Throughout Oregon. CA, ID, NV, WA; throughout most of North America; cool temperate regions worldwide. Exotic. Elymus repens is a strongly rhizomatous, nearly awnless wheatgrass most easily identified by its broad, flat leaves. Occasional individuals of E. lanceolatus and E. trachycaulus have leaf widths overlapping those of E. repens, but (ideally) an examination of the whole stand should reveal the difference. In addition, E. trachycaulus is cespitose. The midvein of the glume in E. repens is scabrous and keeled near the tip but smooth and not truly keeled near the base. In dried specimens, the keel may be observed as a tendency of the midvein to fold over to one side. In our similar native wheatgrasses, the midvein is keeled or not and scabrous or not throughout its length.
Source		Flora of Oregon, volume 1, page 401 Barbara Wilson, Richard Brainerd, Nick Otting
Sibling taxa	E. canadensis, E. ciliaris, E. elymoides, E. glaucus, E. hirsutus, E. lanceolatus, E. multisetus, E. repens, E. trachycaulus, E. tsukushiensis, E. violaceus, E. wawawaiensis	E. canadensis, E. ciliaris, E. elymoides, E. glaucus, E. hirsutus, E. lanceolatus, E. multisetus, E. trachycaulus, E. tsukushiensis, E. violaceus, E. wawawaiensis
Synonyms		Agropyron repens, Elytrigia repens
Web links	Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Elymus macgregorii

Elymus repens

quackgrass

Habit

Plants perennial, 50–100 cm tall, strongly rhizomatous, sometimes glaucous.

Culms

erect to geniculate.

Leaves

sheaths with spreading hairs or glabrous proximally;

blades 6–10 mm wide, usually flat;

lower surfaces glabrous or sparsely pilose;

upper surfaces usually with sparse spreading hairs over the veins but sometimes glabrous.

Inflorescences

5–15 cm, 1 spikelet per node but occasionally with 2 at a few nodes;

internodes 4–6(9.5)mm;

disarticulation above the glumes; beneath each floret.

Spikelets

10–27 mm, appressed to ascending, 4–7 florets.

Glumes

oblong, glabrous; the midveins scabrous and keeled near the tip but smooth and relatively flat near the base; hyaline margins present in the distal half;

tips acute to acuminate; awnless or awned; to 3 mm;

lower glumes 8.8–11.4 mm, 3–6-veined;

upper glumes 7–12 mm, 5–7-veined.

Lemmas

8–12 mm, glabrous, mostly smooth but sometimes minutely scabrous distally; awnless or awned;

lemma awns 0–4(10)mm; straight.

Anthers

4–7 mm.

=22, 42.

Elymus macgregorii

Elymus repens

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas, roadsides, ditches, streamsides. 0–2400m. Throughout Oregon. CA, ID, NV, WA; throughout most of North America; cool temperate regions worldwide. Exotic.

Elymus repens is a strongly rhizomatous, nearly awnless wheatgrass most easily identified by its broad, flat leaves. Occasional individuals of E. lanceolatus and E. trachycaulus have leaf widths overlapping those of E. repens, but (ideally) an examination of the whole stand should reveal the difference. In addition, E. trachycaulus is cespitose. The midvein of the glume in E. repens is scabrous and keeled near the tip but smooth and not truly keeled near the base. In dried specimens, the keel may be observed as a tendency of the midvein to fold over to one side. In our similar native wheatgrasses, the midvein is keeled or not and scabrous or not throughout its length.

Source

Flora of Oregon, volume 1, page 401
Barbara Wilson, Richard Brainerd, Nick Otting

Sibling taxa