Stipa tremula

Description. Perennial plants, densely tufted, with a few culms and numerous vegetative shoots; culms (11 -) 20 - 30 (- 45) cm tall, 1 - 2 (- 3) - noded, nodes distributed close together and only in the lowermost part of the culm. Leaves of vegetative shoots: sheaths glabrous and smooth rarely sparsely and shortly pubescent; ligules truncate, ciliate on the apex, on the external sheaths (0.3 -) 0.7 - 1.1 (- 1.6) mm long, whereas on the internal sheaths, (0.5 -) 1.0 - 2.0 (- 3.0) mm long; blades convolute, green, pale green to greyish, (3 -) 4 - 12 (- 18) cm long, 0.3 - 0.5 (- 0.7) mm in diameter, adaxial surface densely covered by 0.15 - 0.25 mm long hairs, abaxial surface glabrous or scabrous to shortly pilose and grading to almost smooth towards the apex. Cauline leaves: sheaths glabrous and smooth; ligules on the lower sheaths truncate or acute (0.4 -) 1.0 - 1.5 (- 2.1) mm long, on the middle and upper sheaths acute (1.0 -) 1.5 - 2.7 (- 4.0) and 2.0 - 3.1 (- 3.6), respectively; blades convolute, green, pale green or greyish (2.3 -) 2.0 - 3.0 (- 8.9) cm long, adaxial surface covered with short hairs, abaxial surface glabrous, scabrous to shortly pubescent. Panicle (7 -) 11 - 18 (- 26) cm long, open, with (3 -) 6 - 15 (- 18) spikelets, at base enclosed by the sheath of the uppermost leaf or rarely exerted; branches ascending, flexuous, setulose, slightly scabrous to glabrous and smooth, single or paired, 2 - 6 cm long. Glumes subequal (the lower slightly longer than the upper), purplish, (13.0 -) 14 - 17.0 (- 19.5) mm long, lanceolate, with hyaline margins and long tip. Floret (lemma + callus) (7.5 -) 8.4 - 9.5 (- 11.0) mm long and (0.7 -) 0.8 - 1.0 mm wide. Callus (1.5 -) 1.6 - 2.0 (- 2.3) mm long, densely pilose, on ventral part with hairs (0.4 -) 0.5 - 0.8 (- 1.0) mm long, on dorsal with (0.3 -) 0.4 - 0.6 (- 0.8) mm long hairs; callus base 0.5 - 0.8 mm long and 0.15 - 0.25 mm in diameter, sharply pointed, scar narrowly elliptic. Lemma coriaceous, pale-green, purplish or brownish, covered throughout, from the bottom up to 0.5 - 2.3 mm to the top, by dense ascending to appressed hairs 0.3 - 0.8 mm long, above being glabrous (hairless) or with scattered hairs just below the apex; top of lemma glabrous or surpassed by a poorly- to well-developed ring of unequal hairs 0.2 - 0.5 mm long and with (or without) two minute apical lobes. Awn (44 -) 60 - 74 (- 90) mm long, bigeniculate; the lower segment of the awn (column) (6 -) 11 - 15 (- 20) mm long, twisted, 0.3 - 0.4 mm wide at the base, with (1.3 -) 1.7 - 2.0 (- 2.3) mm long hairs, the middle segment of the awn (5 -) 6.5 - 10 (- 13) mm long, twisted, with (1.6 -) 2.0 - 2.3 (- 2.6) mm long hairs; terminal segment of the awn (seta) slightly arcuate or flexuous (26 -) 39 - 53 (- 73) mm long with hairs longer than those on columns, (1.8 -) 2.2 - 2.6 (- 3.1) mm long, gradually decreasing in length towards the apex. Palea equalling lemma in length. Ovary with two styles.