Elytrigia repens

Species

Elytrigia repens (L.) Desv. ex Nevski

Synonyms

(=Agropyron repens (L.) P. Beauv., Elymus repens (L.) Gould)

Family

Poaceae

Tribe

Triticeae

NOTE

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	Elytrigia repens	Pascopyrum smithii
rachilla	strap-like, lies flat against palea, sides parallel or only slightly divergent in basal florets	stands away from palea, sides divergent, flares out towards top
sinus	U-shaped	V-shaped
palea	smoothly concave or with long fold down center	smoothly concave or grooved longitudinally in lower half
lemma back	rounded	keeled
lemma margins	usually do not extend to keels of palea in lower portion	obscure keels of palea in lower portion
lemma above base	with pronounced bulge above base; often slightly keeled just above bulge	with sharp indentation above base; never keeled just above indentation

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)).