Agrostis rigidula var. formosana specimen Credit: cs kuoh

Perennial, branching intra-and /or extra-vaginally at base, reaely with a short rhizome or very short stolona. Culms erect or geniculate at base and rooting at the decumbent nodes, up to 85(-150) cm long. Sheaths smooth; uppermost ligules more or less quadrangular to acute-oblong to triangular, up to 7 mm long, apex truncate to acute, erose or fimbriate; blades erecto-patent to erect, involute or flat, up to 25 cm long, 6.5 mm wide, smooth to scabrous. Panicle contracted to effuse, up to 30 cm long; branches smooth to scabrous, lowermost 1-1 together, the longest 2-11 cm long, ususally many-spikeled, naked in lower part. Spikelets 1.5-4.1(-4.4) mm long. Glumes unequal, the lower longest, ovate-oblong to -lanceolate. Rachilla process absent. Lemma 1.2-3.25 mm long, 0.6-0.8(-0.97) times as long as the lower glume, acutish to truncate and erose, more or less 5-nerved, Trichodium-net developed to asent; callus oblique, small, hairs 0.3 mm long; awn absent or present, then inserted at 0.3-o.8th of the lemma, up to s mm long. Palea 0.1-2 mm long, 0.1-0.75 times as long as the lemma. Anthers (0.4-)1.4(-1.55) mm long, 0.36-0.73(-0.8) times as long as the lemma, yellow to purple.

Four varieties in Taiwan.

Lower Taxa

• Agrostis rigidula var. arisan-montana (Ohwi) Veldk.
• Agrostis rigidula var. formosana (Hack.) Veldk.
• Agrostis rigidula var. fukuyamae (Ohwi) Veldk.
• Agrostis rigidula var. rigidula