Elytrigia repens

Name and classification

Elytrigia repens (L.) Desv. ex Nevski
(=Agropyron repens (L.) P. Beauv., Elymus repens (L.) Gould)
Family Poaceae, Tribe Triticeae

NOTE: This species is actionable only when found in field or vegetable seed for planting; tolerance applies.

Common names

quackgrass, couchgrass

Disseminule

floret, spikelet; disarticulation at base of spikelet, above glumes and between florets

Description

Spikelet laterally compressed, 8–27 mm long, of 3–8 fertile florets and apical sterile florets, rachilla elongated between florets. Glumes 7–12 mm long, cartilaginous or coriaceous, shorter than spikelet; +/– awned, awn to 3 mm. Fertile florets dorsiventrally compressed, with attached rachilla segment, glabrous or sparsely pubescent; lemma coriaceous, thick and lustrous, 8–13 mm long, awnless or with awn up to 10 mm long; palea 80% length of lemma, keels ciliate, apices emarginated, truncate or rounded. Distal sterile florets resemble fertile florets. Caryopsis oblong, dorsiventrally compressed, with ventral face furrowed and dorsal face rounded, 4.5–5.5 mm long, with apical tuft of hairs; embryo 20–25% length of caryopsis, hilum linear, almost length of caryopsis.

Identification considerations

Florets, rather than spikelets, are commonly the disseminule. Rachilla appearance (and other characters) vary greatly depending on position of floret in the spikelet.

Similar species

Pascopyrum smithii (Rydb.) Á. Löve [no images provided] (non-FNW)

Elytrigia repens and Pascopyrum smithii are compared below. Note that the characters described are those of the average "best case" florets and do not account for the many variations seen in the florets.

Character
rachilla
sinus
palea
lemma back
lemma margins
lemma above base

Distribution

widespread in cool north-temperate regions worldwide

native to Europe, northern Africa, and temperate Asia to India

Habitat

cool temperate climate, grows on most soil types; mountain meadows, cultivated fields, orchards, roadsides, disturbed places

General information

Elytrigia repens is an erect, perennial, rhizomatous grass, up to 1.2 m tall. This species spreads by seed unit and by its extensive system of rhizomes. These well-developed rhizomes are the reason it has become one of the most serious weeds in the north-temperate zone. It significantly reduces the crop yields of many crops in many countries. Also, contamination of commercial crop seed production with quackgrass seed units reduces the value of the harvest. Elytrigia repens is one of ten species covered under the Federal Seed Act for which tolerance is applicable to its introduction (7 CFR 361.6(a)(2)).

florets in ventral view (left) and dorsal view (far right)

florets in ventral view (left) and dorsal view (far right)

floret bases showing sinus and rachilla segments

floret bases showing sinus and rachilla segments

floret bases showing bulge

floret bases showing bulge

spikelet

spikelet

caryopsis. A, ventral view; B, lateral view; C, dorsal view; D, transverse section; drawing by Regina O. Hughes

caryopsis. A, ventral view; B, lateral view; C, dorsal view; D, transverse section; drawing by Regina O. Hughes