1	Base of plant with a few very short budlike extravaginal shoots, covered with scales		(2)
+	Base of plant without extravaginal shoots		(7)
2 (1)	Anthers 1.5–2.4 mm; lemmas 2.7–3.5 mm		(3)
+	Anthers 0.7–1.5 mm; lemmas 1.5–3.2 mm		(4)
3 (2)	Lemma glabrous, rarely base minute pubescent; panicle narrow, branches appressed, sometimes slightly spreading.		21 P. przewalskii
+	Lemma base pubescent; panicle more lax; branches spreading after anthesis.		22 P. roshevitsiana
4 (2)	Lemmas 1.5–2 mm, base minutely hairy; anthers 1–1.2 mm; branches of panicle scabrid.		24 P. koeieana
+	Lemmas 2.2–3.2 mm		(5)
5 (4)	Palea keels smooth or with a few spinules on upper part; spikelets usually tinged with purple; panicle spreading after anthesis.		23 P. altaica
+	Palea keels scabrid; spikelets usually pale green; panicle very narrow, contracted		(6)
6 (5)	Lemma base shortly hairy; panicle branches scabrid.		19 P. schischkinii
+	Lemma base glabrous or subglabrous; panicle branches smooth at least on lower parts.		20 P. kuenlunica
7 (1)	Lemmas 1.3–2.4(–2.8) mm		(8)
+	Lemmas 2.5–4 mm		(30)
8 (7)	Anthers 0.3–0.5 mm		(9)
+	Anthers 0.5–1.7 mm		(11)
9 (8)	Branches of panicle smooth.		48 P. micrandra
+	Branches of panicle scabrid		(10)
10 (9)	Lemma base pubescent.		46 P. hauptiana
+	Lemma base glabrous.		47 P. iliensis
11 (8)	Lemma glabrous, rarely with a few hair on callus		(12)
+	Lemmas somewhat pubescent at base		(21)
12 (11)	Anthers 0.5–0.8 mm		(13)
+	Anthers 0.8–1.7 mm		(16)
13 (12)	Branches of panicle scabrid or smooth only near base		(14)
+	Branches of panicle smooth or only in upper part slightly scabrid		(15)
14 (13)	Ligule 2–3 mm, acuminate; panicle 8–12 cm.		44 P. florida
+	Ligule 1–2 mm, obtuse; panicle 5–9 cm.		45 P. leiolepis
15 (13)	Lemmas 2.2–2.4 mm; panicle contracted, 1.5–2.5 × ca. 0.5 cm; culms 5–10 mm tall.		49 P. minuta
+	Lemmas 1.5–2.1 mm; panicle at first contracted but open at maturity, 3–9 × 1–4 cm; culms 5–20 cm tall.		50 P. himalaica
16 (12)	Panicle 3–5 cm, contracted		(17)
+	Panicle 4–15 cm, open		(18)
17 (16)	Culms 10–25 cm tall, not rooting from lower nodes; panicle branches 2–4 per node; anthers 1.2–1.5 mm; apex of palea mucronulate.		15 P. degeensis
+	Culms 5–10 cm tall, rooting from lower nodes; panicle branches single; anthers 0.8–1.2 mm; apex of palea not mucronulate.		16 P. strictura
18 (16)	Plants densely tufted, 20–40 cm tall; basal leaves very numerous, conduplicate, 0.3–0.7 mm wide; plants of sandy habitats.		13 P. filifolia
+	Plants more laxly tufted, 4–15 cm tall; basal leaves less numerous, conduplicate or flat, 1–4 mm wide; plants of non-sandy habitats		(19)
19 (18)	Panicle broadly diffuse, 6–15 cm; branches 2–5 per node, scabrid at least in upper part.		12 P. tenuiflora
+	Panicle less diffuse, 4–10 cm; branches (1 or)2(or 3) per node, smooth		(20)
20 (19)	Lemmas 1.5–2.2 mm, usually violaceous.		14 P. tianschanica
+	Lemmas 2.2–2.5 mm, usually pale pink.		29 P. vachanica
21 (11)	Lowermost internodes of culms thickened, tuberlike; panicle broad and open.		4 P. diffusa
+	Lowermost internodes of culms not tuberlike		(22)
22 (21)	Anthers 0.5–0.9 mm; branches of panicle scabrid, usually reflexed after anthesis		(23)
+	Anthers 0.8–2 mm; branches of panicle scabrid or smooth		(24)
23 (22)	Spikelets in panicle branches very numerous, usually pale green; mostly ruderal plants, rarely found at up to middle montane zone.		42 P. distans
+	Spikelets in panicle branches less numerous, usually grayish or pinkish violet tinge; montane plants.		43 P. glauca
24 (22)	Plants with numerous thin, erect flowering culms, shorter vegetative shoots absent; ligule of upper cauline leaf 2–3.5 mm, gradually narrowed upward.		3 P. tenuissima
+	Flowering culms less numerous, thicker, often geniculate; vegetative shoots usually present; ligule of upper cauline leaf 0.7–2 mm, usually rounded		(25)
25 (24)	Panicle branches scabrid throughout; spikelets usually grayish violet tinge; culms usually geniculate.		2 P. gigantea
+	Panicle branches smooth at least near their base; spikelets pale green or purple-tinged		(26)
26 (25)	Lemmas 2–2.5 mm; anthers 1.2–1.6 mm; spikelets usually pale green; panicle usually hardly exserted from upper sheath.		9 P. coreensis
+	Lemmas 1.5–2.2 mm; anthers 0.9–1.3 mm; spikelets usually purple- tinged; panicle usually broadly open and far exserted from upper sheath		(27)
27 (26)	Plant of high mountains, 10–30 cm tall; panicle branches 1–2 per node; spikelets intense purple.		11 P. qinghaica
+	Plant of lower altitudes, 20–50(–60) cm tall; panicle branches 2–5 per node; spikelets usually less intensely purple		(28)
28 (27)	Lemma densely pubescent near base; palea keels ciliate on lower part, scabrid on upper part; anthers 1.2–1.5 mm.		8 P. chinampoensis
+	Lemma glabrous or slightly pubescent near base; palea keels smooth throughout or scaberulous on upper part; anthers 0.8–1.2 mm		(29)
29 (28)	Lemmas pubescent near base; palea keels scabrid on upper part.		10 P. manchuriensis
+	Lemmas glabrous or subglabrous near base; palea keels usually smooth, rarely with 1–3 small teeth.		12 P. tenuiflora
30 (7)	Lemmas glabrous, rarely with a few hairs on the callus		(31)
+	Lemmas somewhat pubescent at base		(43)
31 (30)	Branches of panicle scabrid or smooth only near base		(32)
+	Branches of panicle smooth or slightly scabrid only on upper part		(35)
32 (31)	Anthers 0.3–0.5 mm.		39 P. micranthera
+	Anthers 1.2–3 mm		(33)
33 (32)	Spikelets with 6–9 florets; culms 30–50 cm tall; anthers 1.2–1.7 mm.		25 P. multiflora
+	Spikelets with 2–5 florets; culms stout, 20–40 cm tall; anthers 1.5–3 mm		(34)
34 (33)	Panicle open, 10–20 cm; anthers 2.3–3 mm; lemmas 3.4–4 mm.		26 P. thomsonii
+	Panicle narrow, 5–10 cm; anthers 1.5–2.2 mm; lemmas 3–3.5 mm.		27 P. stapfiana
35 (31)	Anthers 0.5–1.3 mm		(36)
+	Anthers 1.3–2.5 mm		(39)
36 (35)	Panicle spreading		(37)
+	Panicle contracted and dense		(38)
37 (36)	Culms erect, 20–40 cm tall, very thin; panicle 8–13 cm; branches very thin; lemmas 2.2–2.8 mm.		29 P. vachanica
+	Culms usually geniculately ascending, 10–25 cm tall, rather thick; panicle 5–10 cm; lemmas 2.7–3.5 mm.		34 P. pauciramea
38 (36)	Lemmas 3.2–3.5 mm, palea keels smooth; culms scabrid below inflorescence.		32 P. kashmiriana
+	Lemmas 2.5–3.2 mm; palea keels with a few teeth; culms smooth throughout		33 P. nudiflora
39 (35)	Panicle spreading; branches (1 or)2 per node; leaf blades soft, 1–2 mm wide.		35 P. ladyginii
+	Panicle contracted and dense		(40)
40 (39)	Palea keels ciliate or scabrid; leaf blade soft, smooth, 1.5–2.5 mm wide.		36 P. subspicata
+	Palea keels glabrous and smooth, rarely with a few teeth; leaf blade 0.2– 1.5 mm wide		(41)
41 (40)	Culms 5–8 cm tall, 1-noded; panicle 1–2 cm, branches 1 per node		28 P. shuanghuensis
+	Culms 8–40 cm tall, 2–3-noded; panicle 5–10 cm, branches 1–3 per node		(42)
42 (41)	Culms usually erect, 15–30(–40) cm tall; leaf blade 0.5–1.5 mm broad; spikelets 4–5 mm.		30 P. pamirica
+	Culms geniculate ascending, 8–20 cm tall; leaf blade 0.2–0.5 mm broad; spikelets 5–6 mm.		31 P. ladakhensis
43 (30)	Panicle branches smooth or in upper part some scabrid		(44)
+	Panicle branches scabrid, rarely almost smooth along lower 1/3		(47)
44 (43)	Panicle 1.5–5 cm, contracted and dense; culms 4–15 cm.		41 P. humilis
+	Panicle 5–10 cm, contracted or open; culms 15–40 cm		(45)
45 (44)	Plants of coastal shoals and rocks, marshy meadows; lemma sparsely pubescent along lower part of veins; anthers 0.7–1.2 mm.		38 P. kurilensis
+	Plants of high mountains (3000 m or higher); lemma densely pubescent near base or anthers 1–1.3 mm		(46)
46 (45)	Lemma 2.8–3.5 mm, slightly pubescent near base; anthers 1–1.3 mm.		17 P. roborovskyi
+	Lemma 3.5–4 mm, densely pubescent near base; anthers 0.8–1.2 mm.		18 P. arjinshanensis
47 (43)	Anthers 0.5–0.9(–1) mm		(48)
+	Anthers 1–1.5(–1.8) mm		(49)
48 (47)	Culms straight, 30–80(–100) cm tall; panicle 10–20(–30) cm, branches directed obliquely upward; plants of lowlying, usually seaside, habitats, saltmarshes.		37 P. nipponica
+	Culms usually geniculate, 15–40 cm tall; panicle 5–12(–15) cm, branches usually spreading; plants of montane habitats.		40 P. hackeliana
49 (47)	Ligule of upper cauline leaf 0.7–1.5(–2) mm, apex rounded; culms 30–50 cm tall, rather thick; leaf blades 1.5–3(–4) mm wide		(50)
+	Ligule of the upper cauline leaf 1.7–3.5(–4) mm, gradually narrowed upward		(51)
50 (49)	Lemmas 3–3.5 mm, acuminate.		6 P. jeholensis
+	Lemmas 2.4–3 mm, obtuse.		7 P. macranthera
51 (49)	Leaf blade 0.5–1.2 mm wide, convolute; plants usually without short vegetative shoots; culms thin and straight.		5 P. dolicholepis
+	Leaf blade 1.5–4 mm wide, laxly convolute or flat; plants usually with a few short vegetative shoots; culms thick and geniculate.		1 P. poecilantha