18. Eragrostis trichodes (Nutt.) A.W. Wood (sand love grass, thread love grass)

Pl. 149 h, i; Map 606

E. trichodes var. pilifera (Scheele) Fernald

E. pilifera Scheele

Plants perennial, forming tufts. Flowering stems 30–140 cm long, erect to spreading, glabrous. Leaf sheaths with tufts of hairs on the margins at the tip, otherwise glabrous, the ligule 0.2–0.4 mm long. Leaf blades 15–50 cm long, 1–8 mm wide, flat or less commonly with the margins loosely inrolled, hairy on the upper surface at the base, otherwise glabrous. Inflorescences open, broad panicles 25–50 cm long, usually broadly ovate in outline, the branches loosely ascending to spreading, the axis and main branches smooth and glabrous, rarely with a few hairs in the axils of the main branches, the tips of the branches and spikelet stalks roughened. Spikelets 4–9(–12) mm long, 1.4–2.5(–4.0) mm wide, with slender, short to long stalks, spreading from the branches, with (2–)4–10(–15) perfect florets. Pattern of disarticulation with the glumes and joints of the rachilla usually shed eventually after the lemmas, paleas, and fruits have been shed. Lower glume 1.8–4.0 mm long, lanceolate, usually somewhat roughened along the midnerve. Upper glume 1.8–3.8 mm long, ovate, usually somewhat roughened along the midnerve. Lemmas 2.2–3.5 mm long, ovate, sharply pointed at the tip, keeled, the lateral nerves relatively conspicuous, usually roughened along the midnerve, at least toward the tip. Anthers 0.9–1.6 mm long. Fruits 0.8–1.1 mm long, narrowly oblong in outline, with a relatively broad, deep, longitudinal groove, reddish brown to dark brown. 2n=40. July–October.

Widely scattered in Missouri (Illinois to South Dakota south to Louisiana and Texas). Upland prairies, banks of streams and rivers, and margins of ponds; also old fields, railroads, ditches, and open, usually moist, disturbed areas.

Steyermark noted that E. trichodes can be distinguished from other perennial species of Eragrostis, such as E. hirsuta, E. intermedia, and E. spectabilis, by its relatively long lower glume. In portions of the Great Plains, it is considered a desirable grass as forage for livestock.

Two specimens (from St. Francois County and St. Louis) differ from typical E. trichodes as represented in Missouri. These robust plants have longer spikelets (8–12 mm) with more florets (9–15) and also tend to have inflorescences positioned well above the leaves. They correspond to E. trichodes var. pilifera, a taxon reported to occur sporadically at sandy sites within the range of var. trichodes. Because both specimens originate from highly disturbed habitats, such as mine tailings, it is suspected that they represent introduced populations. Although the plants appear quite distinct from other Missouri specimens of E. trichodes, elsewhere the two taxa apparently intergrade freely, and var. pilifera is reduced to synonymy here and in most of the other literature treating the species (Harvey, 1948; Gould, 1975; Witherspoon, 1975; Sutherland, 1986; Gleason and Cronquist, 1991).