Key 1

1	Staminodes 3-5- or 7-23-branched, branches with globose glands at apex.		(2)
+	Staminodes terete and divided at apex or not, or flat and 5-7-dentate or 2- or 3- or 5-lobed at apex, apex usually eglandular.		(12)
2 (1)	Staminodes 7-23-branched		63 P. palustris
+	Staminodes 3- or 5-branched.		(3)
3 (2)	Staminodes 3-branched; cauline leaves 2 or more.		(4)
+	Staminodes (3-)5(or 7)-branched; cauline leaf 1.		(7)
4 (3)	Leaf blade broadly oblanceolate to narrowly ovate; petals rhomboid, margin subentire or undulate		53 P. rhombipetala
+	Leaf blade reniform; petals not rhomboid, margin fimbriate proximally or throughout.		(5)
5 (4)	Petal margin fimbriate proximally; cauline leaves 3-6		54 P. amoena
+	Petal margin fimbriate throughout; cauline leaves 2-8.		(6)
6 (5)	Petals oblanceolate or oblong, marginal fimbriae turgid at apex, becoming clavate; cauline leaves usually 2-5		55 P. noemiae
+	Petals ovate or triangular-ovate, marginal fimbriae not turgid at apex; cauline leaves usually more than 3		56 P. foliosa
7 (3)	Petal margin fimbriate throughout; staminodes divided for 1/3-1/2 their length.		(8)
+	Petal margin slightly undulate, or fimbriate proximally and undulate or entire distally; staminodes divided for up to 1/2 their length or more.		(9)
8 (7)	Leaf blade ovate-cordate, thick textured, base cordate		61 P. perciliata
+	Leaf blade ovate or reniform, thin textured, base often truncate or subcordate		62 P. davidii
9 (7)	Petal margin slightly undulate; basal leaf blade ovate to oblong-ovate		57 P. guilinensis
+	Petal margin fimbriate proximally, undulate or entire distally; basal leaf blade ovate-cordate to broadly orbicular.		(10)
10 (9)	Basal leaf blade broadly orbicular, obviously wider than long		60 P. longshengensis
+	Basal leaf blade ovate-cordate, about as long as wide.		(11)
11 (10)	Staminodes divided nearly to base		58 P. gansuensis
+	Staminodes divided for ca. 1/2 their length		59 P. simaoensis
12 (1)	Staminodes terete, apex divided or not.		(13)
+	Staminodes flat, apex 5-7-dentate or (2 or)3(or 5)-lobed, usually eglandular.		(24)
13 (12)	Staminodes terete, apex 2-lobed and ± 2-labiate.		(14)
+	Staminodes terete, apex entire, rounded or discoid.		(15)
14 (13)	Basal leaf blade 6-15 mm, broadly obovate, broadly ovate, or broadly rhomboid-ovate; staminodes 2-lobed, posterior lobes 2- or 3-lobed		11 P. faberi
+	Basal leaf blade 2-3 mm, rhomboid, ovate-rhomboid, or suborbicular; staminodes 2-lobed, posterior lobes 2-5-lobed		12 P. labiata
15 (13)	Basal leaves numerous, forming a rosette.		(16)
+	Basal leaves few, 3-5(-8), not forming a rosette.		(17)
16 (15)	Petals broadly elliptic; staminodes knoblike at apex; sepals oblong; cauline leaf borne near middle of stem		9 P. petitmenginii
+	Petals narrowly obovate-spatulate; staminodes sublingulate at apex; sepals lanceolate; cauline leaf borne near apex of stem		10 P. esquirolii
17 (15)	Basal leaf blade reniform or deeply cordate, rarely cordate at base; petals green.		(18)
+	Basal leaf blade ovate-cordate, ovate-reniform, or ovate-triangular, cordate or attenuate at base; petals white or green.		(19)
18 (17)	Plants 15-30 cm tall; petals lanceolate to oblong-lanceolate, 14.5-22.5 × 4.5-5.5 mm; leaf blade 2-6 × 5-9.5 cm		1 P. longipetala
+	Plants 5-11 cm tall; petals broadly obovate, 4-8 × 3-6 mm; leaf blade 0.8-2.5 × 1.3-3 cm		2 P. tenella
19 (17)	Petals green or yellow-green.		(20)
+	Petals white or yellowish.		(22)
20 (19)	Petals yellow-green; cauline leaf cordate-reniform; basal leaf blade ovate-reniform		5 P. longipetaloides
+	Petals green; cauline leaf oblong or ovate-lanceolate; basal leaf blade ovate-cordate or ovate-reniform.		(21)
21 (20)	Petals densely purple-brown punctate; staminodes rounded at apex; basal leaf blade ± ovate-cordate		3 P. angustipetala
+	Petals not punctate; staminodes truncate or emarginate at apex; basal leaf blade mostly ovate-reniform		4 P. yulongshanensis
22 (19)	Petals minutely purple-brown punctate, often emarginate at apex; staminodes often indistinctly 3-crenate at apex or entire		6 P. yunnanensis
+	Petals not punctate, acute or rounded at apex; staminodes rounded at apex.		(23)
23 (22)	Staminodes broad and flat; basal leaf blade ovate-cordate, base cordate; cauline leaf borne near apex of stem, much smaller than basal leaves; petals yellowish		7 P. yanyuanensis
+	Staminodes thin and long; basal leaf blade ovate-triangular, base attenuate; cauline leaf borne near base of stem, slightly smaller than or subequaling basal leaves; petals white		8 P. humilis
24 (12)	Staminodes 5-7-dentate at apex.		(25)
+	Staminodes (2 or)3(-5)-lobed at apex.		(26)
25 (24)	Petals broadly spatulate or obovate, margin erose or subentire, base with a claw ca. 1 mm wide; leaf blade cuneate or subcordate at base		13 P. degeensis
+	Petals triangular-ovate, margin long fimbriate proximally, base with a long claw; leaf blade deeply cordate at base		14 P. farreri
26 (24)	Staminodes 2- or 5-lobed at apex.		(27)
+	Staminodes 3(-5)-lobed at apex, lobes usually eglandular, rarely inconspicuously glandular at apex.		(33)
27 (26)	Staminodes 2-lobed at apex, lobes subequal; cauline leaves 2		46 P. bifolia
+	Staminodes 5-lobed at apex, lobes equal or unequal; cauline leaf 1.		(28)
28 (27)	Petal margin sparsely and shortly fimbriate throughout; stem not more than 10 cm		52 P. omeiensis
+	Petal margin long fimbriate proximally; stem more than 10 cm.		(29)
29 (28)	Staminodes 5-lobed or 5-parted at apex, lobes unequal.		(30)
+	Staminodes 5-lobed to middle, lobes subequal.		(31)
30 (29)	Petals yellow-white; leaf blade reniform		50 P. yiliangensis
+	Petals white; leaf blade ovate-cordate		51 P. chengkouensis
31 (29)	Basal leaf blade oblong-cordate or broadly cordate		49 P. monochoriifolia
+	Basal leaf blade broadly cordate, broadly orbicular, or suborbicular.		(32)
32 (31)	Basal leaf blade broadly orbicular, rarely suborbicular, usually wider than long, rarely as wide as long; cauline leaf broadly ovate or reniform		48 P. dilatata
+	Basal leaf blade reniform, broadly cordate, or broadly ovate, about as wide as or wider than long; cauline leaf similar in shape to basal ones		47 P. wightiana
33 (26)	Connective of anther apically projected into a lanceolate appendage.		(34)
+	Connective of anther not apically projected.		(36)
34 (33)	Basal leaf blade ovate-cordate or ovate; staminodes 3-lobed for 1/4-1/3 their length, central lobe narrower than lateral ones; styles usually short, not exserted beyond staminodes, occasionally longer		43 P. brevistyla
+	Basal leaf blade reniform or suborbicular; staminodes 3-lobed or -parted, lobes subequal; styles usually long, exserted beyond staminodes, rarely shorter.		(35)
35 (34)	Staminodes 3-lobed to middle or almost so; basal leaf blade reniform or suborbicular		44 P. delavayi
+	Staminodes 3-parted beyond middle; basal leaf blade reniform		45 P. leptophylla
36 (33)	Cauline leaves absent.		(37)
+	Cauline leaves 1 or 2.		(38)
37 (36)	Staminodes lobed for ca. 1/3 their length, lobes narrow; petals yellow, apex emarginate or 2-lobulate; leaf with 3 parallel veins		15 P. lutea
+	Staminodes lobed for ca. 1/5 their length, lobes short and broad, central one longer than lateral ones; petals white, apex rounded-obtuse; leaf usually with 5 parallel veins		16 P. scaposa
38 (36)	Cauline leaves 2		42 P. lijiangensis
+	Cauline leaf 1.		(39)
39 (38)	Staminodes 3-lobed at apex, lobes unequal.		(40)
+	Staminodes 3(-5)-lobed at apex, lobes equal or subequal.		(41)
40 (39)	Central lobe of staminode much shorter than lateral ones; petals greenish, narrowly oblong, margin sparsely and shortly fimbriate; cauline leaf borne distally on stem		39 P. cooperi
+	Central lobe of staminode longer than lateral ones; petals white, obovate, rarely subspatulate, margin entire; cauline leaf borne near base of stem		40 P. laxmannii
41 (39)	Petal margin long fimbriate proximally.		(42)
+	Petal margin entire or shortly fimbriate and erose proximally.		(45)
42 (41)	Basal leaf blade obovate or oblong-obovate		41 P. obovata
+	Basal leaf blade reniform, orbicular, broadly ovate-orbicular, ovate-cordate, or occasionally other shapes.		(43)
43 (42)	Basal leaf blade ovate-cordate, 2-4.5 × 1.8-3.5 cm, thick textured, subleathery		19 P. crassifolia
+	Basal leaf blade reniform, orbicular, or broadly ovate-orbicular, rarely ovate-cordate.		(44)
44 (43)	Basal leaf blade orbicular or broadly ovate-orbicular, base cordate with a deep sinus, apex obtuse and apiculate; cauline leaf much smaller than basal ones; petals oblanceolate, with 2 green, oblong glands near base, apex acute		17 P. yui
+	Basal leaf blade reniform, rarely ovate-cordate, apex rounded, rarely subobtuse or emarginate; cauline leaf about as large as basal ones; petals obovate, eglandular, apex emarginate		18 P. chinensis
45 (41)	Petal margin shortly fimbriate proximally.		(46)
+	Petal margin erose or entire.		(47)
46 (45)	Sepals and petals purple-brown punctate; petals 5-6 × 3-4 mm; basal leaf blade 9-10 × 8-9 mm		21 P. venusta
+	Sepals and petals not punctate; petals 7.8-9.5 × 5.2-6.1 mm; basal leaf blade 1-1.5 cm × 9-14 mm		20 P. epunctulata
47 (45)	Ovary superior.		(48)
+	Ovary semi-inferior.		(54)
48 (47)	Basal leaf blade oblong or elliptic, truncate or cuneate at base.		(49)
+	Basal leaf blade ovate-reniform, -cordate, -oblong, or broadly ovate, cordate at base.		(50)
49 (48)	Basal leaf blade oblong, 8-9 × 4-5 mm; petals spatulate		23 P. filchneri
+	Basal leaf blade elliptic, 1.8-6 × 1-2.5 cm; petals suborbicular or elliptic		24 P. xinganensis
50 (48)	Petals green, lanceolate, margin minutely and densely purple punctate, densely erose, apex acuminate		25 P. lanceolata
+	Petals white, obovate, margin sparsely erose or entire, apex rounded or cleft.		(51)
51 (50)	Basal leaf blade ovate-reniform; plants not more than 4 cm tall		26 P. kangdingensis
+	Basal leaf blade ovate-cordate, ovate-oblong, or broadly ovate; plants usually more than 4 cm tall.		(52)
52 (51)	Petals usually cleft or emarginate at apex; staminodes 3-lobed for ca. 1/3 or occasionally ca. 1/2 their length		27 P. mysorensis
+	Petals rounded at apex; staminodes shallowly 3-lobed for ca. 1/6 their length.		(53)
53 (52)	Plants 16-27 cm tall; basal leaf blade ovate-oblong or broadly ovate, deeply cordate at base, 2-9-veined; staminodes 3(-6)-lobed, lobes truncate at apex, central one narrower than lateral ones		28 P. submysorensis
+	Plants 7-10 cm tall; basal leaf blade ovate, densely brown punctate, with 5-7 arcuate veins; staminodes 3-lobed, lobes rounded at apex		29 P. cacuminum
54 (47)	Basal leaf blade ovate-cordate to reniform, base usually cordate.		(55)
+	Basal leaf blade oblong, base not cordate.		(59)
55 (54)	Stem usually more than 28 cm; basal leaf blade ovate-cordate, 3-4.1 cm, deeply cordate at base		30 P. cordata
+	Stem usually 2-8 cm, occasionally to 20 cm; basal leaf blade not more than 2 cm.		(56)
56 (55)	Petals pale yellow-green		22 P. qinghaiensis
+	Petals white.		(57)
57 (56)	Basal leaf blade reniform, rarely ovate-cordate; cauline leaf borne near middle of stem; staminode lobes lanceolate		31 P. pusilla
+	Basal leaf blade ovate-cordate; cauline leaf borne near base of stem; staminode lobes oblong.		(58)
58 (57)	Petals broadly obovate, purple punctate; stem less than 6 cm; basal leaf petiole ca. 1 cm, leaf blade usually cordate at base		35 P. subscaposa
+	Petals obovate, not or indistinctly punctate; stem 8-20 cm; basal leaf petiole (1.5-)3-6 cm, leaf blade usually truncate at base		36 P. deqenensis
59 (54)	Stem relatively low; basal leaves small.		(60)
+	Stem relatively tall; basal leaves large.		(61)
60 (59)	Petals white; basal leaf petiole 8-15(-40) mm, leaf blade usually cuneate at base		37 P. trinervis
+	Petals green; basal leaf petiole (1-)15-25 mm, leaf blade usually subcordate at base		38 P. viridiflora
61 (59)	Staminodes 3-parted for ca. 2/3 their length, lobes parallel, to 3.2 mm		32 P. oreophila
+	Staminodes 3-lobed for 1/5-1/4 their length.		(62)
62 (61)	Staminodes broad, lobes linear, ca. 1 mm; petals yellow		33 P. tibetana
+	Staminodes narrow, lobes lanceolate or ovate-lanceolate, ca. 1.5 mm; petals white		34 P. nubicola