1	Callus obtuse or conical; lemma 2-toothed at the tip		(2)
+	Callus acuminate, pungent, rarely blunt S.sibirica); lemma entire at the tip		(7)
2 (1)	Awn glabrous throughout its length or thinly hairy on the column		(3)
+	Awn plumose throughout its length		(6)
3 (2)	Glumes conspicuously unequal		(4)
+	Glumes ± equal		(5)
4 (3)	Lemma 4.8-5.7 mm long, the apical teeth 0.5-1.3 mm long; awn 6-12 mm long		Stipa splendens
+	Lemma 9-10 mm long, the apical teeth c.2.5 mm long; awn 16-20 mm long		Stipa chitralensis
5 (3)	Panicle loose and spreading, the branches bare in the lower half to two-thirds		Stipa caragana
+	Panicle narrow, the branches short and ascending, spiculate to the base		Stipa jacquemontii
6 (2)	Panicle very loose and open, the branches and pedicels capillary, spreading; awn bigeniculate, 15-30 mm long		Stipa mongholica
+	Panicle narrow and ± contracted, the branches and pedicels erect, not capillary; awn unigeni culate, 10-15 mm long		Stipa concinna
7 (1)	Glumes lanceolate, acute or slightly acuminate, not much longer than the lemma (c. 1.5 times as long)		(8)
+	Glumes narrowly lanceolate and long-acuminate, much longer than the lemma (2-4 times as long)		(10)
8 (7)	Leaf-blades flat, 3.5-8(-12) mm wide; spikelets pallid or green		Stipa sibirica
+	Leaf-blades involute and setaceous, no more than 1 mm wide when flattened; spikelets deeply suffused with purple		(9)
9 (8)	Awn with plumose column (hairs up to 1 mm long) and shortly hairy bristle (hairs 0.2-0.3 mm long)		Stipa regeliana
+	Awn with long-plumose column (hairs 25-3.5 mm long) and scaberulous bristle		Stipa subsessiliflora
10 (7)	Annual; awns at length twisted together to form a tail at the summit of the panicle		Stipa capensis
+	Perennial; awns not twisted together into a tail (except in S. consanguinea)		(11)
11 (10)	Awn scabrid throughout its length or with hairs not more than 0.8 mm long		(12)
+	Awn either plumose throughout its length with longest hairs (1.5-)3-7 mm long or partly plumose and partly smooth, scabrid or very shortly hairy		(14)
12 (11)	Awns at length entangled to form a tail at the summit of the panicle, shortly puberulous throughout their length; lemma 8-10 mm long, with a crown of short stiff hairs at the tip		Stipa consanguinea
+	Awns not becoming entangled to form a tail		(13)
13 (12)	Awn scabrid throughout its length; lemma 10-14 mm long, smooth towards the top and without a crown of stiff hairs at the tip		Stipa capillata
+	Awn shortly plumose (hairs not exceeding 0.8 mm) throughout its length; lemma 5-7 mm long, spinulose-scabrid towards the top and with a crown of stiff hairs at the tip		Stipa breviflora
14 (11)	Awn unigeniculate with a rigidly falcate bristle		Stipa caucasica
+	Awn bigeniculate; bristle often flexuous or recurved but not rigidly falcate		(15)
15 (14)	Glumes lanceolate, shortly acuminate, deeply suffused with purple		(16)
+	Glumes narrowly lanceolate and long-acuminate, green or silvery, but not deeply suffused with purple(though sometimes faintly tinged)		(17)
16 (15)	Panicle loose with long, flexuous, ± filiform branches		Stipa purpurea
+	Panicle narrow, linear with short, stiff, rigidly erect branches		Stipa roborowskyi
17 (15)	Awn plumose, or at least shortly hairy, throughout its length		(18)
+	Awn with plumose bristle, but smooth or scabrid column		(20)
18 (17)	Awn 3.5-7 cm long		Stipa orientalis
+	Awn (9-)10-20 cm long		(19)
19 (18)	Hairs on column of awn 0.5-1 3 mm long		Stipa arabica
+	Hairs on column of awn 2-3 mm long		Stipa himalaica
20 (17)	Lemma 11-13 mm long		Stipa trichoides
+	Lemma (13-) 15-25 mm long		Stipa kirghisorum