1	Sepals persistent after flowering; keel with apical appendage highly filiform-fimbriate		(2)
+	Sepals caducous after flowering, rarely one outer sepal persistent; keel with apical appendage flabelliform and lobed or laciniate (flowers unknown in P. oligosperma)		(20)
2 (1)	Filaments united, forming an open staminal sheath split in upper 1/2-2/3, with 2 separate single filaments in middle, and on either side of these, a united group of 3 filaments each carrying 3 sessile anthers at tip		(3)
+	Filaments united throughout their length forming an open staminal sheath, or united in lower 1/3-2/3 forming an open staminal sheath with upper 1/3-2/3 free or grouped into 2 lobes		(5)
3 (2)	Annual herbs, usually shorter than 15 cm tall; racemes axillary or extra-axillary, shorter than leaves; flowers white, rarely purple-red, lateral petals deltoid-rhombic, margin sometimes undulate; capsule ca. 2 mm in diam., minutely winged.		30 P. polifolia
+	Perennial herbs, erect, more than 15 cm tall; racemes terminal or pseudoterminal, rarely axillary, longer than leaves; flowers purple-red, lateral petals oblong or elliptic, margin not undulate; capsule ca. 4 mm in diam., obviously winged		(4)
4 (3)	Petals 2; stamens 6-8; capsule margin ciliate; strophiole 3-lobed; leaf blade 3-4 mm wide.		31 P. monopetala
+	Petals 3; stamens 8; capsule margin not ciliate; strophiole 2-lobed; leaf blade 0.5-1(-3) mm wide.		32 P. tenuifolia
5 (2)	Filaments united for entire length, forming an open staminal sheath		(6)
+	Filaments united in lower 1/2-2/3, forming an open staminal sheath, upper 1/3-1/2 free		(9)
6 (5)	Racemes terminal; lateral petals much longer than carina; style apex penicillate; capsule oblong; seeds densely sericeous.		26 P. hybrida
+	Racemes axillary, extra-axillary, or opposite to leaf; lateral petals equaling or shorter than carina; style apex not penicillate; capsule orbicular or obcordate; seeds pubescent		(7)
7 (6)	Leaf blade subleathery or thickly papery, lateral veins 3-5 pairs, raised on both surfaces; racemes opposite to leaves; capsule orbicular, emarginate, ca. 6 mm in diam., broadly winged, not ciliate.		29 P. japonica
+	Leaf blade papery, lateral veins obscure on both surfaces; racemes extra-axillary; capsule obcordate or suborbicular, ca. 4 mm in diam., narrowly winged and ciliate		(8)
8 (7)	Leaf blade lanceolate to linear-lanceolate, both surfaces green.		27 P. lhunzeensis
+	Leaf blade broadly ovate to orbicular, abaxially purple-red, adaxially dark green.		28 P. wenxianensis
9 (5)	Plants densely hairy with at least some long spreading hairs		(10)
+	Plants hairy, hairs curved pubescent, not long, or plant glabrescent		(11)
10 (9)	Perennial herbs; leaves alternate, elliptic or obovate-elliptic, apex obtuse or retuse; racemes 1.2-2 cm; petals free, apical appendages not stalked.		33 P. crotalarioides
+	Annual herbs; leaves subopposite, broadly ovate to oblong-elliptic, apex obtuse, mucronate; racemes 0.5-1 cm; petals basally connate, apical appendages stalked.		34 P. subopposita
11 (9)	Apex of style extended, obliquely cup-shaped or horseshoe-shaped, stigma 1		(12)
+	Apex of style not cup-shaped or horseshoe-shaped, stigmas 2		(14)
12 (11)	Style obliquely cup-shaped, with a terminal tuft of hairs at apex; stem indumentum glandular; leaves in upper branches alternate, lower ones subopposite or pseudowhorled.		35 P. paniculata
+	Style horseshoe-shaped, not hairy; stem indumentum not glandular; leaves alternate		(13)
13 (12)	Slender herbs, prostrate; leaf blade membranous, lanceolate to linear-lanceolate, 10-20 × 2.5-3 mm, both surfaces glabrous; flowers 3.5-4.5 mm; capsule obovoid-ellipsoidal, ca. 2.5 mm in diam..		36 P. triflora
+	More robust herbs, erect; leaf blade papery, obovate or elliptic to lanceolate, 2.6-10 × 1-1.5 cm, sparsely pubescent; flowers ca. 4.5 mm; capsule orbicular, ca. 2 mm in diam..		37 P. chinensis
14 (11)	Annual herbs		(15)
+	Perennial herbs		(16)
15 (14)	Stems slender, narrowly winged or ridged; lower leaves ovate, dense, upper leaves lanceolate to linear-lanceolate, sparse, less than 0.5 cm wide; racemes terminal.		38 P. longifolia
+	Stems relatively stout, terete; leaves lanceolate or linear-lanceolate, evenly alternate, more than 0.5 cm wide; racemes in forks of branches.		39 P. persicariifolia
16 (14)	Leaf blade shiny, lateral veins conspicuous, raised on both surfaces		(17)
+	Leaf blade not shiny, lateral veins inconspicuous		(18)
17 (16)	Stems caespitose, branched or not; leaf blade linear-lanceolate or elliptic-lanceolate, 3-5 mm wide [in Nepal, leaves to 8 mm wide]; racemes terminal or axillary; bracts linear, persistent at flowering; inner sepals ovate-oblong to elliptic-oblong.		43 P. elegans
+	Stems simple or multibranched; leaf blade lanceolate or elliptic-lanceolate to ovate, 5-10 mm wide; racemes opposite to leaves or axillary; bracts ovate-lanceolate, caducous; inner sepals obovate-oblong.		44 P. bomiensis
18 (16)	Stems, branchlets, and inflorescences erect-pubescent; apex of inner sepals acute; capsule narrowly winged.		42 P. sibirica
+	Stems, branchlets, and inflorescences crisped pubescent; apex of inner sepals mucronate to acuminate; capsule broadly winged		(19)
19 (18)	Racemes terminal, 3-6 cm, 7-18-flowered; flowers 7-9 mm; inner sepals obliquely ovate, apex rounded.		40 P. hongkongensis
+	Racemes opposite to leaves, 1.5-2 cm, 3-8-flowered; flowers ca. 6 mm; inner sepals obovate, apex acuminate, falcate.		41 P. lijiangensis
20 (1)	Racemes terminal, pseudoterminal, or opposite to leaf, sometimes a panicle; apical appendage laciniate; unwinged part of capsule usually with obvious concentric ribs; seeds globose, strophiole hooded or helmet-shaped		(21)
+	Racemes axillary or terminal, appendage lamellate; unwinged part of capsule without obvious concentric ribs; seeds ovoid or hirsute-villous, not strophiolate, or pubescent and strophiolate		(27)
21 (20)	Scandent shrubs; flowers in terminal panicles.		1 P. tricholopha
+	Erect shrubs; flowers in terminal, pseudoterminal, or leaf-opposed racemes		(22)
22 (21)	Both surfaces of leaf blade glabrous; capsule with 1 maturing seed.		2 P. oligosperma
+	Both surfaces of leaf blade pubescent, at least on veins; capsule with 2 seeds		(23)
23 (22)	Branchlets, petioles, and inflorescence axes glabrous or sparsely pubescent		(24)
+	Branchlets, petioles, and inflorescence axes densely pubescent		(25)
24 (23)	Leaf blade elliptic, (5-)10-16 × 4.5-6.5 cm, lateral veins 7 or 8 pairs and reticulate veins slightly raised on both surfaces; racemes axillary; capsule reniform, depressed at both ends.		6 P. didyma
+	Leaf blade obovate to elliptic, (10-)15-19 × 5.5-7 cm, lateral veins 6 or 7 pairs, raised only abaxially, reticulate veins flat; racemes terminal or opposite to leaves; capsule reniform-orbicular, base rounded, depressed only at apex.		7 P. globulifera
25 (23)	Racemes leaf-opposed; inner sepals oblong to ovate, at right angle to petals, apical appendage stalkless; capsule winged.		3 P. arillata
+	Racemes terminal; inner sepals obliquely ovate, not at right angle to petals, apical appendage stalked; capsule not winged		(26)
26 (25)	Leaf blade lanceolate to elliptic-lanceolate, smaller than 20 × 7 cm; lateral petals oblong, apex nearly truncate, inside glabrous at base; capsule obcordate to orbicular, 1-1.4 cm in diam..		4 P. fallax
+	Leaf blade ovate, larger than 25 × 8 cm; lateral petals broadly elliptic, apex rounded, inside barbate at base; capsule broadly ovoid, ca. 1 cm in diam..		5 P. barbellata
27 (20)	Annual herbs (rarely small shrubs), with corymbose branches from middle of stems; one outer sepal persistent after flowering (P. tatarinowii with completely caducous outer sepals)		(28)
+	Shrubs or subshrubs; usually all outer sepals caducous after flowering		(34)
28 (27)	Flowers red or purple-red, keel without conspicuous apical appendage; capsule pubescent; seeds strophiolate, without appendage or tubercle.		19 P. tatarinowii
+	Flowers yellow, keel with apical appendage; capsule glabrous; seeds normally with strophiole, appendage, and tubercle		(29)
29 (28)	Racemes 7-14 cm at fruiting; seeds glabrous		(30)
+	Racemes shorter than 5 cm at fruiting; seeds pubescent		(32)
30 (29)	Plant branching from upper part of stem, corymbose, branchlets thin; leaf blade ovate-deltoid or ovate; capsule broadly obcordate, ca. 2 mm across; seeds ovoid, tuberculate or punctate, without wings.		25 P. isocarpa
+	Plant branching from lower part of stem, branchlets stout; leaf blade ovate; capsule subglobose or subsquare, apex retuse, winged; seeds with appendage		(31)
31 (30)	Stem not fleshy; capsule globose or subsquare, ca. 3 mm across; seeds ellipsoidal, exotesta tuberculate, with a black, shiny appendage.		23 P. lacei
+	Stem fleshy; capsule subglobose, ca. 4 mm across; seeds oblong, smooth, not tuberculate, with a small, white appendage.		24 P. carnosicaulis
32 (29)	Small shrubs; keel with boat-shaped apical appendage.		20 P. bawanglingensis
+	Annual herbs; keel with bow-shaped or fan-shaped apical appendage		(33)
33 (32)	Bracts subulate; inner sepals elliptic, 3-3.5 mm; seeds ellipsoid, tuberculate, with obvious, black, shiny, oblong appendage.		21 P. umbonata
+	Bracts ovate; inner sepals obovate, ca. 2.5 mm; seeds ovoid, smooth, not tuberculate, without obvious appendage.		22 P. furcata
34 (27)	Apical appendage of keel peltate or saccate-cucullate; seeds densely hirsute-villous, strophiole absent		(35)
+	Apical appendage of keel shallowly lobed; seeds pubescent, with winged strophiole		(37)
35 (34)	Capsule yellowish with raised resiniferous punctate glands; leaves evenly arranged on branchlets.		8 P. resinosa
+	Capsule neither yellowish nor with resiniferous punctate glands; leaves usually concentrated at apices of branchlets		(36)
36 (35)	Flowers 5(-8) mm; apical appendage of keel peltate; capsule oblong-obovate, ca. 8 mm, ca. 4 mm in diam..		9 P. caudata
+	Flowers 12-20 mm; apical appendage of keel 2-cucullate; capsule obovate or cuneate, 10-14 mm, ca. 6 mm in diam..		10 P. wattersii
37 (34)	Shrubs; leaf blade linear-lanceolate or elliptic-lanceolate; flowers 2-2.5 cm.		11 P. karensium
+	Erect herbs or subshrubs; leaf blade elliptic, obovate, or variously lanceolate; flowers less than 1.5 cm		(38)
38 (37)	Petals white or yellow; outer sepals differing in size; middle outer sepal pocketlike or cucullate		(39)
+	Petals pink or purple-red; outer sepals nearly equal, ovate or elliptic, or middle one small and boat-shaped		(40)
39 (38)	Petals white or greenish white; flowers at least 15 mm, middle outer sepal and apical appendage of keel cucullate; stems with dense, raised leaf scars and lenticels; leaf blade slightly fleshy, elliptic-obovate to spatulate, 5-6 mm wide, apex obtuse.		12 P. dunniana
+	Petals yellow; flowers ca. 7 mm; middle outer sepal and apical appendage of keel pocketlike; stems without leaf scars and lenticels; leaf blade membranous, elliptic-lanceolate, ca. 3 cm wide, apex acuminate.		13 P. arcuata
40 (38)	Outer sepals unequal, middle one small and boat-shaped		(41)
+	Outer sepals nearly equal, ovate or elliptic		(42)
41 (40)	Keel 2-lamellate; boat-shaped outer sepal not winged on midvein; capsule suborbicular, ca. 4.5 mm in diam.; leaf blade lanceolate or elliptic, 3-12 × 1-3.5 cm.		17 P. hainanensis
+	Keel 4-lamellate; boat-shaped outer sepal narrowly winged on midvein; capsule orbicular to subsquare, ca. 5 mm in diam.; leaf blade obovate or narrowly elliptic, 4.5-9 × 2.5-4.5 cm.		18 P. saxicola
42 (40)	Flowers ca. 4 mm, keel with papillate apical appendage; inner sepals obovate to orbicular.		14 P. wuzhishanensis
+	Flowers 6-9 mm, keel with lamellate apical appendage; inner sepals elliptic or elliptic-ovate		(43)
43 (42)	Keel lamellate, with 3-lobed apical appendage; petals connate in lower 3/4; leaf blade ovate-, obovate-, or elliptic-lanceolate, 3.5-8 × 1.5-2.5 cm, abaxially dark purple, base oblique.		15 P. latouchei
+	Keel 2-lamellate, with 2-lobed apical appendage; petals connate in lower 1/2; leaf blade elliptic, 1.5-4 × 0.6-1.5 cm, abaxially greenish and purplish, base rounded, not oblique.		16 P. koi