126. Cleistogenes Keng, Sinensia. 5: 147. 1934.
隐子草属 yin zi cao shu
Authors: Shou-liang Chen & Sylvia M. Phillips
Kengia Packer, nom. illeg. superfl.
Perennial. Culms usually tufted, many-noded. Leaf blades linear or linear-lanceolate, often inrolled when dry, lower blades usually disarticulating from the sheaths; ligule a line of hairs, sometimes on a very short membranous base. Inflorescence of often few-spiculate lax racemes spaced along a central axis, or a sparsely branched panicle, spikelets distant or loosely imbricate, shortly pedicellate; axillary cleistogamous spikelets also present concealed within the upper leaf sheaths. Spikelets laterally compressed, florets 1 to several, loosely spaced, rachilla slender, disarticulating above glumes and between florets, rachilla internodes pubescent at apex; glumes membranous, very unequal with the lower shorter, 1–5(–7)-veined; lemmas narrowly lanceolate to ovate, 3–5(–7)-veined, keeled, usually pubescent near margins, apex narrow, bidenticulate or rarely entire, acute, mucronate or shortly awned; palea keels glabrous or ciliolate. Floret callus shortly bearded. Anthers 3, linear.
About 13 species: S Europe and Turkey eastward through C Asia, Pakistan, and NW India to Japan, concentrated in NE China; ten species (five endemic) in China.
A large proportion of the species comprises plants of semi-arid regions, where they provide useful fodder. The genus is remarkable for the regular formation of cleistogamous spikelets in the axils of the upper leaf sheaths that ensure the production of seed even under unfavorable climatic conditions. These cleistogamous spikelets generally have fewer florets, smaller, hyaline glumes, and narrower lemmas with longer awns than the chasmogamous spikelets.
The glumes are very variable even in the terminal, exserted inflorescences. Those of the lower spikelets, near the inflorescence base, tend to be smaller and fewer nerved than those above. Spikelets near the top of the inflorescence should be inspected. Awn measurements should be taken on the lowest floret of a spikelet near the top.