Poaceae
Elymus

Elymus riparius Wiegand

First published in Rhodora 20: 84 (1918)
This species is accepted
The native range of this species is SE. Canada, N. Central & E. U.S.A. to NE. Mexico. It is a perennial and grows primarily in the temperate biome.

Descriptions

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: not threatened. Confidence: confident
[AERP]

Morphology General 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.
Morphology Reproductive morphology Inflorescences
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.
Morphology Reproductive morphology Inflorescences 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.
Fertile
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.
Morphology Reproductive morphology Inflorescences Bracts Glume
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.
Morphology Reproductive morphology Flowers 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.
Morphology Reproductive morphology Flowers
Lodicules 2; membranous. Anthers 3. Stigmas 2.
Morphology Reproductive morphology Fruits
Hilum linear.
Distribution
North America: eastern Canada, northwest USA, north-central USA, northeast USA, southwest USA, southeast USA, and Mexico.
Reference
Triticeae. Man US Grasses 2000.
[GB]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • GrassBase - The Online World Grass Flora

    • Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora.
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Herbarium Catalogue Specimens

    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2026. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2026. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0