Montana Field Guide

PLANTS: Bunchgrass. Stems are 80–130 cm tall. Sources: Barkworth et al. in Flora of North America [FNA] 2007; Lesica et al. 2012.

LEAVES: Blades are 5–12 mm wide, flat, and spreading or lax. Leaf sheaths are usually glabrous, rarely hirsute. Ligules are less than 1 mm long. Auricles are absent. Sources: Barkworth et al. in FNA 2007; Lesica et al. 2012.

INFLORESCENCE: A terminal bilateral spike with more than one spikelet per node, 6-12 cm long. The rachis is continuous and erect. Spikelets are usually 2 per node, 10–13 mm long, and disarticulate below the glumes. Glumes are distinctly broadest in the lower half and taper to a short awn or awn-tip. Glumes have 3 to 5 veins, a yellowish base (1 mm) that is distinctly indurate (bony), round in cross-section, and outwardly curving. Lemmas are mostly 2 to 4 per spikelet, essentially hairless, 6-9 mm long, and bear a straight awn of 10–20 mm long. Sources: Barkworth et al. in FNA 2007; Lesica et al. 2012.

Pollen is typically released (anthesis) around mid-June to late July, sometimes mid-August (Barkworth et al. in FNA 2007).

For Elymus virginicus 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.

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.
*Spikelets are 10-13 mm long. Basal 1-2 mm of glume is bony (shatters from the seed-head), yellowish, and outwardly curved. Grows in regularly disturbed sites that are not in the mountains. Compare these characteristics with Elymus glaucus.

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.

Blue Wildrye - Elymus glaucus, native
*Spikelets are 12-20 mm long. Basal 1-2 mm of glume is not bony, mostly greenish, and not outwardly curved. Grows in undisturbed dry meadows and open understories in the mountains. Compare these characteristics with Elymus virginicus.

Shady moist understory settings at lower elevations (Lesica et al. 2012).