Silky Wild Rye
Grass family (Poaceae)
Description: This native perennial grass is 2½–3½' tall and unbranched, often forming tufts of culms at the base. Each culm is green, glabrous, and terete (round in cross-section). The blades of the alternate leaves are up to 9" long and nearly ½" across; they are linear, dark green, and slightly hairy. The leaf sheaths are green, finely ribbed, and covered with spreading white hairs. The apex of each sheath wraps tightly around the culm, where there is a pair of auricles (ear-like extensions of the sheath).
Each culm terminates in a nodding raceme of spikelets about 3-4" long. The base of each spikelet consists of a pair of narrowly linear and awned glumes about ¾–1" long (including their awns) and up to 1 mm. across; they spread outward, giving the inflorescence a bristly appearance. Above the glumes, there are 1-2 pairs of linear and awned lemmas; these lemmas are about 1¼–1½" long (including their awns). Each fertile lemma has a membranous palea about ¼" long that encloses the developing grain. Both the glumes and the lemmas are more or less covered with patches of fine hairs. The spikelets are whitish green while the flowers are in bloom, and shortly later they become tan. The blooming period occurs during the summer. Each spikelet produces 1-2 elongated grains. The root system is fibrous.
Cultivation: The preference is partial sun to light shade, moist to slightly dry conditions, and a fertile loamy soil.
Range & Habitat: Silky Wild Rye is a common grass that occurs in every county of Illinois (see Distribution Map). Habitats include deciduous woodlands, woodland borders, rocky wooded slopes, savannas, small meadows in wooded areas, and thickets. This grass is usually found in higher quality wooded habitats.
Faunal Associations: The flowers are wind-pollinated and attract few insects. The caterpillars of the moth Leucania pseudargyria (False Wainscot) and the leafhopper Laevicephalus orientalis feed on Elymus spp. (Wild Ryes). Birds apparently pay little attention to the seeds as a food source. Livestock eat the foliage of Wild Ryes, but the awns of the seedheads can cause mechanical injury to their mouthparts and gastrointestinal tracts.
Photographic Location: Along a path in a wooded area of Meadowbrook Park in Urbana, Illinois.
Comments: Silky Wild Rye is an attractive woodland grass. It is one of several Elymus spp. (Wild Ryes) in Illinois. As a group, these grasses have large bristly inflorescences; they are cool-season grasses with a C3 metabolism, maturing by mid-summer. Silky Wild Rye can be distinguished from Elymus virginicus (Virginia Wild Rye) by its nodding inflorescence; the latter has an erect inflorescence. Similarly, Silky Wild Rye can be distinguished from an uncommon species, Elymus riparius (Riverbank Wild Rye), by its hairy sheaths; the sheaths of the latter species are hairless. Another species, Elymus canadensis (Canada Wild Rye), is a more robust grass that has broader glumes (often 1.0–2.0 mm. across), while the glumes of Silky Wild Rye are 1.0 mm. across or less. There is a rare form of Silky Wild Rye, f. arkansansus, that has hairless lemmas.