Elymus riparius

HABIT Perennial; caespitose. Rhizomes absent. Culms slender; 100–150 cm long. Leaf-sheaths glabrous on surface. Ligule an eciliate membrane. Leaf-blades 5–15 mm wide. Leaf-blade surface scabrous.

INFLORESCENCE Inflorescence composed of racemes.

Racemes 1; single; drooping; bilateral; 7–20 cm long. Rhachis flattened. Spikelet packing broadside to rhachis. Rhachis internodes oblong.

Spikelets in pairs. Fertile spikelets sessile; 2 in the cluster.

FERTILE SPIKELETS Spikelets comprising 2–3 fertile florets; with diminished florets at the apex. Spikelets elliptic to oblong; laterally compressed; 10–12 mm long; breaking up at maturity; disarticulating below each fertile floret.

GLUMES Glumes persistent; similar; reaching apex of florets. Lower glume lanceolate; 10 mm long; 1 length of upper glume; coriaceous; without keels; 2–4 -veined. Lower glume apex attenuate; awned; 1 -awned. Lower glume awn 10–15 mm long. Upper glume lanceolate; 10 mm long; coriaceous; without keels; 2–4 -veined. Upper glume lateral veins ribbed. Upper glume apex attenuate; awned; 1 -awned. Upper glume awn 10–15 mm long.

FLORETS Fertile lemma lanceolate; 10–12 mm long; coriaceous; without keel; 5 -veined. Lemma surface smooth, or scaberulous. Lemma apex attenuate; awned; 1 -awned. Principal lemma awn straight; subterete below; 20–30 mm long overall. Palea 0.7–0.9 length of lemma; 2 -veined. Apical sterile florets resembling fertile though underdeveloped.

FLOWER Lodicules 2; membranous. Anthers 3. Stigmas 2.

FRUIT Hilum linear.

DISTRIBUTION North America: eastern Canada, northwest USA, north-central USA, northeast USA, southwest USA, southeast USA, and Mexico.

NOTES Triticeae. Man US Grasses 2000.

Please cite this publication as detailed in How to Cite Version: 3rd February 2016.