87. Hordeum (barley)
(Baum and Bailey, 1990; von Bothmer
et al., 1991)
Plants annual or perennial (short‑lived), lacking
rhizomes, forming tufts. Flowering stems erect to ascending or spreading,
glabrous. Leaf sheaths glabrous or hairy, the ligule short, membranous. Leaf
blades flat, glabrous or roughened to hairy, sometimes with a pair of auricles
at the base. Inflorescences erect or arched to nodding, often with the base
enclosed in the uppermost leaf sheath, with numerous erect to ascending or
spreading spikelets spaced densely along opposite sides of the axis, the
internodes 1.5–3.0 mm long. Spikelets in clusters of 3 at each node, the
central spikelet fertile, with 1 perfect floret, the 2 lateral spikelets
sterile and with reduced, small florets (except sometimes in Hordeum
vulgare, with all 3 spikelets perfect), linear in outline, disarticulating
at the nodes of the inflorescence axis (except in Hordeum vulgare), the
joints shed as a unit with the attached spikelets. Glumes similar in size and
appearance, linear or awnlike, usually somewhat hardened at the base, the tip
with a long or short, roughened awn (except sometimes in H. vulgare),
glabrous or roughened to hairy. Lemmas with the tip awned (except sometimes in H.
vulgare), rounded on the back, faintly 5‑nerved, the body thickened
and hard, glabrous or roughened. Paleas lanceolate, as long as or slightly
shorter than the body of the lemmas. Fruits, linear to elliptic, usually
slightly flattened and grooved, hairy at the tip, yellowish brown. About 32
species, North America, South America, Europe, Asia, Africa.
A number of intergeneric hybrids between Hordeum and Elymus
species have been reported in the literature, but only one of these has been
found in Missouri thus far (see discussion under the treatment of E.
trachycaulus). Other hybrids are to be expected in Missouri.