9. Cleistogenes hackelii (Honda) Honda, Bot. Mag. (Tokyo). 50: 437. 1936.
朝阳隐子草 chao yang yin zi cao
Culms loosely tufted from a knotty base with scaly buds, erect, very slender to moderately stout, 30–90 cm tall, 0.5–1.5 mm in diam., often branched above base, internodes often purple. Leaf sheaths mostly shorter than internodes, pilose above middle with tubercle-based hairs or glabrous; leaf blades linear-lanceolate, thin, flat, patent, 3–15 × 0.3–1 cm, glabrous or thinly pilose, acute; ligule 0.3–0.5 mm. Panicle open, exserted, 4–10 cm; branches few, laxly spreading, lowest branch 2–5 cm. Spikelets 5–9 mm, florets 2–5; glumes lanceolate or lanceolate-ovate; lower glume 0.5–3 mm, 0–1-veined, obtuse to acute; upper glume wide, 1–4.7 mm, 1–3-veined (or terminal spikelet 3–5-veined), narrowly obtuse to acute; lemmas lanceolate, lowest 4–6 mm, usually with dark transverse blotches, pilose along lower margins and keel, emarginate; awn 2–9 mm; palea keels scabrid. Fl. and fr. Jul–Nov. 2n = 40.
Hill slopes in forests, along forest margins. Anhui, Fujian, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Zhejiang [Japan, Korea].
This is a rather tall species with a sparse panicle, found in shady places. The spikelets are distinguished by the small, hyaline glumes and relatively long awns, although awn length is very variable. The scaly basal buds are an obvious feature. Japanese specimens (var. hackelii) are relatively uniform, but in China the species is much more variable and often slightly more robust with thicker culms and larger leaf blades (var. nakaii). It forms part of an intergrading complex with Cleisto-genes hancei, which has a larger, open panicle, often with secondary branching, and spikelets with longer, acuminate glumes and shorter awns.