Montana Field Guide

This excerpt is for Elymus curvatus which is adapted from the Flora of North America (Barkworth et al. in FNA 2007).

PLANTS: Cespitose perennials; culms 60-110 cm tall, stiffly erect or sometimes geniculate at base.

LEAVES: Leaf sheaths glabrous, often reddish brown; auricles to 1 mm or absent; ligules less than 1 mm long, ciliolate; blades 5-15 mm wide, upper surface smooth to somewhat scabrous.

INFLORESCENCE: Spikes 9-15 cm long, up to 1.3 cm wide, erect, exserted or the bases slightly inserted; spikelets 2 per node. Spikelets 10-15 mm long, appressed, often reddish brown at maturity; florets (2)3-4(5) (only the lowest functional). Glumes equal or subequal, 7-15 mm long, the basal 2-3 mm portion indurate (hardened), terete, 1.2-2.1 mm wide and without evident venation, the upper portion of glume bodies widening and becoming 3-5 veined and strongly bowed out; disarticulation below glumes and beneath florets. Lemmas 6-10 mm long, glabrous or scabrous (rarely hirsute), awns straight and mostly 1-4 mm (rarely 5-10 mm on lemmas of uppermost spikelets); paleas 6-10 mm, obtuse, often emarginate. Anthers 1.5-3 mmm long.

Elymus virginicus var. submuticus was elevated to the species level by Kartesz (1999) which also included plants previously treated as Elymus virginicus var. submuticus (https://explorer.natureserve.org/). The 2007 Flora of North America treatment places these plants as Elymus curvatus (Barkworth et al. in FNA 2007). Clear distinctions in morphology are not always maintained across their ranges which leads to professional judgements in how to understand their genetic relationships.

The MTNHP follows the treatment used in the draft revised Manual of Montana Vascular Plants, which lumps Elymus curvatus, Elymus submuticus, and Elymus virginicus var. submuticus together because short-awned plants do not always align with differences in leaf morphology for Montana specimens and anthesis is seldom known or could vary across distributions (Lesica et al. 2012). However, any observation submitted under the name Elymus curvatus will be tracked in our database by that name.

Awnless Wildrye - Elymus curvatus, native
*Lemma awns are 0.5-3(4) mm long. Upper leaves usually ascend and are somewhat involute. Lower leaves are relatively shorter, narrower, and senesce earlier than upper leaves. Anthesis occurs from late June to early August or 1-2 weeks later than Elymus virginicus. Compare these characteristics with Elymus virginicus.

Virginia Wildrye - Elymus virginicus, native
*Lemma awns are 5-15 (20) mm long. All leaf blades are flat, and spreading or lax. Lower leaves are not noticeably larger or more persistent than upper leaves. Anthesis occurs from mid-June to mid-August or 1-2 weeks earlier than Elymus curvatus. Compare these characteristics with Elymus curvatus.

Across its range it has been found in moist or damp soils of open forests, thickets, grasslands, ditches, and disturbed ground, especially in bottomlands (Barkworth et al. in FNA 2007).