Elymus repens (L.) Gould

synonyms: Agropyron repens


couch grass, quackgrass


Info

Subfamily: Pooideae
Genus etymology: Elymus is the ancient Greek name for a unidentified cereal grass
Species etymology: repens = "creeping" [Latin] refering to the rhizomes
Photosynthetic type: C3 (cool season)
Nativity: naturalized - intentional
First recorded in Hawaiʻi: 1988
Legal status: HDOA - noxious weed

Map

 Distribution of Elymus repens in Hawaiʻi.

Inflorescence

Elymus repens Inflorescence

Habit

Elymus repens Habit

Spikelets

Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets
Elymus repens Spikelets

Rhizomes

Elymus repens Rhizomes

Description

Plants strongly rhizomatous, sometimes glaucous. Culms 50-100 cm. Leaves sometimes somewhat basally concentrated; sheaths pilose or glabrous proximally; auricles 0.3-1 mm; ligules 0.25-1.5 mm; blades 6-10 mm wide, usually flat, abaxial surfaces glabrous or sparsely pilose, adaxial surfaces usually sparsely pilose over the veins, sometimes glabrous, veins smooth, widely spaced, primary veins prominent, separated by the secondary veins. Spikes 5-15 cm long, 0.5-1.5 cm wide, erect, usually with 1 spikelet per node, occasionally with 2 at a few nodes; internodes 4-6(9.5) mm long, 0.5-1.2 mm wide, smooth or scabrous, glabrous, evenly puberulent, or sparsely pilose, hairs to 0.3 mm. Spikelets 10-27 mm, appressed to ascending, with 4-7 florets; disarticulation above the glumes, beneath each floret. Glumes oblong, glabrous, keeled distally, keels inconspicuous and smooth proximally, scabrous and conspicuous distally, lateral veins inconspicuous, hyaline margins present in the distal 1/2, apices acute, unawned or awned, awns 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, sometimes scabridulous distally, unawned or with a 0.2-4(10) mm awn, awns straight; paleas 7-9.5 mm, keels ciliate from 1/2 to almost the entire length, apices emarginate, truncate, or rounded; anthers 4-7 mm. 2n = 22, 42.
(Description source: Barkworth, M.E., Capels, K.M. & Long, S. (eds.) 1993. Flora of North America, north of Mexico. Volume 24. Magnoliophyta: Commelinidae (in part): Poaceae, Part 1. Oxford University Press, New York. 911 pp. http://floranorthamerica.org/Elymus_repens )