1. Lolium perenne L. (perennial rye grass, English rye grass)
Pl. 178
a–c; Map 721
Plants annual, forming tufts, or perennial, with sterile
offsets produced from short stolons, forming clumps. Flowering stems 30–120 cm
long. Leaf sheaths with the ligule 0.5–2.5 mm long. Leaf blades 2–15(–25) cm
long, 1–6 mm wide. Inflorescences 5–25 cm long, the axis roughened along the
angles and sometimes on the surfaces. Spikelets 5–22 mm long, with 4–22
florets. Glume 4–12 mm long, mostly less than 2/3 as long as the rest of the
spikelet, relatively soft. Lemmas with the body 3.5–9.0 mm long, mostly 4–8
times as long as wide, oblong‑lanceolate to oblong‑oblanceolate in
outline, sharply to bluntly pointed (sometimes split into 2 small teeth) at the
tip, awnless or with an awn 0.5–15.0 mm long. Anthers 2.0–4.5 mm long. Fruits
2.5–5.5 mm long, relatively slender, about 3–5 times as long as wide. 2n=14,
28. May–August.
Introduced, widely scattered in Missouri (native of Europe, cultivated nearly worldwide). Pastures, roadsides, railroads, and open, disturbed
areas.
This species is planted as a pasture grass for forage and
hay. For a discussion of potential problems with it as a forage grass, see the
paragraph on endophytic fungi at the head of the genus Festuca. It also
is a component of seed mixes for lawns and as a temporary soil cover for
erosion control, especially along roadsides. Steyermark (1963) noted that it
may be an important causal agent of hay fever.
Lolium perenne consists of annual and perennial variants that have been
treated as separate species by some authors and combined by others. These are
recognized as varieties in the present treatment.