1	Lateral leaflets 1 pair	2
–	Lateral leaflets 2–7 pairs	21
2	Lower leaflet surfaces densely pannose, hairs < 0.2 mm long	3
–	Lower leaflet surfaces sparsely to densely pilose, sericeous, strigose, tomentose or villous, hairs 0.4–2.0 mm long	10
3	Leaflet margins crenate	4
–	Leaflet margins entire or serrate	6
4	Stipular sheaths apically acute, outer sheath surfaces densely villous	P.incana
–	Stipular sheaths apically truncate, outer sheath surfaces glabrous to densely villous	5
5	Leaflets obovate; upper leaflet surfaces and rachises tomentose; central Peru	P.fjeldsaoi
–	Leaflets elliptic; upper leaflet surfaces and rachises villous; southern Peru	P.pallidistigma
6	Leaflets 0.7–1.2 cm long; inflorescences 0.7–1.5 cm long	7
–	Leaflets 1.3–3.2 cm long; inflorescences 2.2–8.0 cm long	8
7	Leaflets 1.0–1.2 cm long; upper leaflet surfaces often with dark sheen, glabrous to sparsely villous; central Bolivia	P.nana
–	Leaflets 0.7–0.8 cm long; upper leaflet surfaces rugose, glabrous, usually covered with a layer of yellowish resinous exudate; south-western Peru, north-western Chile, western Bolivia and north-western Argentina	P.tarapacana
8	Stipular sheaths with outer surfaces densely tomentose; 13–15 stamens per flower; fruits with 2–4 wide flattened hard irregular ridges, sparsely tomentose	P.crista-galli
–	Stipular sheaths with outer surfaces glabrous to densely villous; 15–23 stamens per flower; fruits with 3–4 ridges with a variable number and placement of flattened spines, densely villous	9
9	Leaflets 0.5–0.7 cm wide, with 7–15 teeth per side; leaflet apices obtuse to slightly acute; upper leaflet surfaces glabrous; 5–7 flowers per inflorescence; 15–19 stamens per flower; Dpto. Cochabamba (Bolivia)	P.incanoides
–	Leaflets 0.3–0.6 cm wide, with 5–10 teeth per side, leaflet apices round to emarginate; upper leaflet surfaces glabrous to sparsely villous; 4–5 flowers per inflorescence, 19–23 stamens per flower; Dptos. Potosi, Oruro, Chuquisaca, Tarija (Bolivia) and Jujuy (Argentina)	P.tomentella
10	Leaflet margins serrate	11
–	Leaflet margins entire or crenate	13
11	Lower leaflet surfaces sparsely to densely tomentose without underlying short hairs; 7–21 flowers per inflorescence	P.racemosa
–	Lower leaflet surfaces densely tomentose with a dense underlying layer of very short white hairs; 3–7 flowers per inflorescence	12
12	Leaflets 0.7–1.3 cm wide; leaflet apices acute; inflorescences 5.1–7.5(–8.9) cm long; Titicaca basin (Puno, Peru; La Paz, Bolivia)	P.incarum
–	Leaflets 0.4–0.6 cm wide; leaflet apices obtuse to emarginate; inflorescences 1.8–3.7 cm long; Depts. Cochabamba and north-western Potosi (Bolivia)	P.subtusalbida
13	Leaflets 0.9–2.2 cm long; leaflet apices deeply emarginate without projection; Ecuador	P.reticulata
–	Leaflets 0.9–3.3 cm long; leaflet apices round, obtuse, acute or emarginate with a mid-vein projection; Ecuador, Peru, Bolivia, Chile	14
14	Leaflet margins entire	15
–	Leaflet margins crenate	16
15	Leaflets 0.9–1.1 × 0.4–0.6 cm; upper leaflet surfaces glabrous to sparsely sericeous; lower leaflet surfaces sparsely to densely sericeous; inflorescences 0.9–1.1 cm long, with 1 flower	P.rodolfovasquezii
–	Leaflets (1.3–)1.7–2.8 × 0.5–0.7 cm; upper leaflet surfaces sparsely strigose; lower leaflet surfaces densely strigose; inflorescences (1.9–)2.5–4.9(–5.6) cm long, with 3–6 flowers	P.subsericans
16	Lower leaflet surfaces densely tomentose with a dense underlying layer of very short, white pannose hairs	17
–	Lower leaflet surfaces densely pilose, villous or tomentose without pannose hairs	18
17	Upper leaflet surfaces smooth to slightly rugose; lower leaflet surface hairs 0.6–0.8 mm long; 7–9 flowers per inflorescence; central Bolivia	P.besseri
–	Upper leaflet surfaces strongly rugose; lower leaflet surface hairs 0.8–1.0 mm long; 4–5 flowers per inflorescence; south-western Peru and north-western Chile	P.rugulosa
18	Upper leaflet surfaces sparsely to densely pilose; 3–5 flowers per inflorescence; 11–17 stamens per flower	19
–	Upper leaflet surfaces glabrous to sparsely villous; 5–13 flowers per inflorescence; 19–23 stamens per flower	20
19	Lower leaflet surfaces densely pilose, hairs 0.5–0.6 mm long	P.flavipila
–	Lower leaflet surfaces densely villous, hairs 1.0–1.2 mm long	P.pilosissima
20	Leaflet apices round to emarginate; upper leaflet surfaces sparsely villous; lower leaflet surfaces densely villous, hairs 0.9–11 mm long; inflorescences 2.0–4.0 cm long, with 5–7 flowers; south-central Peru	P.acomayensis
–	Leaflet apices acute; upper leaflet surfaces glabrous; lower leaflet surfaces densely tomentose, hairs 0.4–0.8 mm long; inflorescences (4.9–)5.5–7.0(–9.5) cm long, with 11–13 flowers; southern Peru and northern Bolivia	P.triacontandra
21	Lateral leaflets 4–7 pairs	22
–	Lateral leaflets 2–3 pairs	38
22	Lower leaflet surfaces glabrous to puberulous; fruits with 2–3(–4) irregular and pronounced, thin wings	P.neglecta
–	Lower leaflet surfaces sparsely or densely lanate, sericeous, villous or tomentose, hairs 0.3–2.3 mm long; fruits with variable numbers of flattened or long, hard spines	23
23	Leaflets 0.3–0.7 cm long; leaflet apices deeply emarginate; inflorescences 3.8–5.3 cm long, with 1–3 flowers	P.microphylla
–	Leaflets 1.1–5.4 cm long; leaflet apices slightly emarginate to emarginate; inflorescences 2.4–36.0 cm long, with 4–83 flowers	24
24	Lower leaflet surfaces sparsely or densely sericeous	25
–	Lower leaflet surfaces densely lanate, villous or tomentose	31
25	Leaflet margin entire or serrate	26
–	Leaflet margin slightly crenate to crenate	28
26	Leaflets (0.8–)1.1–1.5 cm wide; lower leaflet surface hairs 1.3–1.7 mm long	P.canoi
–	Leaflets 0.4–0.9 cm wide; lower leaflet surface hairs 0.2–0.9 mm long	27
27	Leaflets broadly obovate; upper leaflet surfaces glabrous with few hairs on the mid-vein	P.loxensis
–	Leaflets narrowly elliptic to elliptic; upper leaflet surfaces glabrous to sparsely sericeous	28
28	Lateral leaflet 3–4 pairs	29
–	Lateral leaflet 4–7 pairs	30
29	Leaflet margins slightly crenate at the apex; inflorescences 3.9–6.6(–7.8) cm long, with 18–21 flowers; northern Peru	P.albicans
–	Leaflet margins entire; inflorescences 13.0–17.9(–20.4) cm long, with 23–29 flowers; central Ecuador	P.humboldtii
30	Leaflets 1.6–3.0 cm long; leaflet margins entire to slightly serrate; lower leaflet surfaces of mature plants with hairs 0.3–0.5 mm long; north-western Ecuador and southern Colombia	P.ochreata
–	Leaflets (1.1–)1.4–1.6 cm long, leaflet margins crenate; lower leaflet surfaces of mature plants with hairs 0.3–0.4 mm long; north-eastern Ecuador	P.pauta
31	Lower leaflet surfaces densely lanate or villous, the hairs 0.7–1.8 mm long	32
–	Lower leaflet surfaces densely tomentose, the hairs 0.3–1.5 mm long	35
32	Leaflet margin entire to slightly crenate; northern Ecuador	P.longipilosa
–	Leaflet margins serrate; northern Colombia, Peru	33
33	Leaflets 0.4–0.8 cm wide, obovate; leaflet apices slightly emarginate; 7–15 flowers per inflorescence; north-western Colombia	P.frontinensis
–	Leaflets 0.8–2.0 cm wide, elliptic; leaflet apices acute or obtuse; 16–83 flowers per inflorescence; Peru	34
34	Leaflets 1.1–2.0 cm wide; leaflet apices obtuse; lower leaflet surfaces densely villous; inflorescences (15.4–)21.7–28.2(–36.0) cm long, with 47–83 flowers	P.multijuga
–	Leaflets 0.8–1.0(–1.2) cm wide; leaflet apices acute; lower leaflet surfaces densely lanate; inflorescences (7.6–)9.5–13.3(–17.3) cm long, with 16–35 flowers	P.serrata
35	Leaflet apices moderately emarginate; upper leaflet surfaces sparsely tomentose; Bolivia and Argentina	P.hieronymi
–	Leaflet apices deeply emarginate; upper leaflet surfaces glabrous; Colombia, Ecuador and Peru	36
36	Lateral leaflets (1–)2–3(–4) pairs; lower leaflet surface hairs 0.6–1.5 mm long; Ecuador	P.reticulata
–	Lateral leaflets 3–5 pairs; lower leaflet surface hairs 0.3–0.9 mm long; Colombia and Peru	37
37	Leaflets 0.5–0.8 cm wide; lower leaflet surface hairs 0.3–0.6 mm long; inflorescences 2.4–6.7 cm long, with 4–12 flowers; northern Peru	P.occidentalis
–	Leaflets 0.7–1.1 cm wide; lower leaflet surface hairs 0.7–0.9 mm long; inflorescences (6.0–)7.3–10.5(–12.3) cm long, with 11–19 flowers; north-eastern Colombia	P.quadrijuga
38	Lower leaflet surfaces glabrous to sparsely hispid, puberulous, or pannose, the hairs < 0.2 mm long	39
–	Lower leaflet surfaces sparsely to densely lanate, sericeous, tomentose or villous, the hairs 0.3–2.5 mm long	42
39	Leaflets 0.5–0.8 cm wide; leaflet margins crenate, with 5–8 teeth per side; lower leaflet surfaces glabrous to sparsely villous; southern Peru	P.pallidistigma
–	Leaflets 0.4–1.5 cm wide; leaflet margins serrate with 9–18 teeth per side; lower leaflet surfaces glabrous; Argentina and Bolivia	40
40	Leaflet margins with 12–18 teeth per side; leaflet apices acute; 14–27 flowers per inflorescence; Argentina and Bolivia	P.neglecta
–	Leaflet margins with 9–13 teeth per side; leaflet apices obtuse to emarginate; 5–12 flowers per inflorescence	41
41	Leaflets elliptic, lower leaflet surfaces glabrous to sparsely hispid; fruits with 2–3 irregular and pronounced thin wings, glabrous; Argentina	P.australis
–	Leaflets obovate, lower leaflet surfaces pannose; fruits with 2–4 wide flattened hard irregular ridges, sparsely tomentose; Argentina and Bolivia	P.crista-galli
42	Lower leaflet surfaces densely lanate, the hairs 1.3–2.5 mm long	43
–	Lower leaflet surfaces sparsely to densely sericeous, tomentose or villous, the hairs 0.3–2.0 mm long	45
43	Leaflets elliptic; upper leaflet surfaces glabrous to sparsely lanate; lower leaflet surface hairs 1.5–2.5 mm long, yellowish; 13–16 flowers per inflorescence; Ecuador	P.lanuginosa
–	Leaflets obovate to broadly obovate; upper leaflet surfaces sparsely lanate; lower leaflet surface hairs 1.3–1.5 mm long, whitish; 5–11 flowers per inflorescence; Peru and Bolivia	44
44	Leaflets (1.8–)2.2–2.7 × 0.9–1.4 cm; inflorescences (5.0–)6.1–4.9(–12.3) cm long; Bolivia	P.lanata
–	Leaflets 1.6–2.6 × 0.6–1.1 cm; inflorescences 5.0–8.8 cm long; Peru	P.sacra
45	Lower leaflet surfaces densely sericeous, the hairs 0.2–1.7 mm long	46
–	Lower leaflet surfaces sparsely to densely tomentose or villous, the hairs 0.4–2.0 mm long	52
46	Leaflets 0.8–1.3 × 0.2–0.7 cm; inflorescences 1.2–1.6(–3.5) cm long, with 3 flowers; southern Peru and Bolivia	P.pepei
–	Leaflets 1.2–3.9 × 0.4–1.5 cm; inflorescences 3.3–20.4 cm long, with 5–29 flowers; Venezuela to Bolivia	47
47	Leaflets (2.4–)3.4–3.9 × (0.8–)1.1–1.5 cm; lower leaflet surface hairs 1.3–1.7 mm long, yellowish; central Peru to Bolivia	P.canoi
–	Leaflets 1.2–2.8 × 0.4–1.0 cm; lower leaflet surface hairs 0.2–1.0 mm long, silky, whitish; Venezuela to central Peru	48
48	Lateral leaflets 3–5 pairs; lower leaflet surface hairs 0.2–0.6 mm long; Ecuador and north-western Peru	49
–	Lateral leaflets 2–3 pairs; lower leaflet surface hairs 0.6–1.0 mm long; Venezuela, Colombia, central Peru	51
49	Leaflet margins entire; inflorescences 13.0–17.9(–20.4) cm long, with 23–29 flowers	P.humboldtii
–	Leaflet margins slightly crenate at the apex or serrate; inflorescences 3.5–12.2 cm long, with 9–27 flowers	50
50	Leaflets elliptic; leaflet margins slightly crenate at the apex; north-western Peru	P.albicans
–	Leaflets broadly obovate; leaflet margins serrate; southern Ecuador	P.loxensis
51	Leaflets (1.9–)2.4–2.6 × 0.5–0.7 cm; upper leaflet surface sparsely to dense sericeous; inflorescences 7.2–8.1 cm long; central Peru	P.argentea
–	Leaflets 1.8–2.1 × 0.8–1.0 cm; upper leaflet surfaces glabrous; inflorescences 3.3–4.5 cm long; Venezuela and Colombia	P.sericea
52	Leaflet margins serrate	53
–	Leaflet margins entire to crenate	55
53	Lateral leaflets 3–4(5) pairs; lower leaflet surface densely villous; Colombia	P.frontinensis
–	Lateral leaflets 1–2 pairs; lower leaflet surfaces sparsely to densely tomentose; Ecuador, Peru and Bolivia	54
54	Leaflets (2.3–)3.1–3.9 × (0.7–)0.9–1.5 cm, apices round; inflorescences (4.2–)5.0–9.4(–11.7) cm long, with 7–21 flowers; Ecuador and Peru	P.racemosa
–	Leaflets 0.9–1.6 × 0.4–0.6 cm, apices obtuse to emarginate; inflorescences 1.8–3.7 cm long, with 3–4 flowers; Bolivia	P.subtusalbida
55	Leaflet apices acute, round, obtuse or emarginate; lower leaflet surfaces densely tomentose or villous with a dense underlying layer of very short pannose hairs; Peru and Bolivia	56
–	Leaflet apices moderately to deeply emarginate; lower leaflet surfaces densely tomentose without short pannose hairs; Ecuador to Argentina	59
56	Lower leaflet surface hairs 0.9–1.1 mm long; inflorescences 2.0–4.0 cm long; central Peru	P.acomayensis
–	Lower leaflet surface hairs 0.4–0.9 mm long; inflorescences 3.6–10.0 cm long; southern Peru to Bolivia	57
57	Leaflets (2.0–)2.6–3.3 × 0.7–1.1 cm, narrowly elliptic; 11–13 flowers per inflorescence; Dptos. Puno (Peru) and La Paz (Bolivia)	P.triacontandra
–	Leaflets 1.4–2.4 × 0.6–11 cm, narrowly obovate; 5–11 flowers per inflorescence; La Paz and Cochabamba (Bolivia)	58
58	Lateral leaflets 1–2(–3) pairs; stipular sheaths apically truncate; rachises and lower leaflet surfaces densely villous; Dpto. Cochabamba (Bolivia)	P.besseri
–	Lateral leaflet 2–3 pairs; stipular sheaths apically acute; rachises and lower leaflet surfaces densely tomentose; Dpto. La Paz (Bolivia)	P.pacensis
59	Leaflets (0.9–)1.3–1.6 × (0.4–)0.7–1.1 cm, broadly ovate; Ecuador	P.simpsoniae
–	Leaflets 0.9–2.2 × 0.4–1.1 cm, elliptic to obovate; Colombia to Argentina	60
60	Leaflets narrowly obovate; upper leaflet surfaces sparsely tomentose; Bolivia and Argentina	P.hieronymi
–	Leaflets narrowly elliptic to obovate; upper leaflet surfaces glabrous; Colombia to Peru	61
61	Lower leaflet surface hairs 0.3–0.6 mm long; Peru	62
–	Lower leaflet surface hairs 0.6–1.5 mm long; Colombia and Ecuador	63
62	Lateral leaflets 3–5 pairs; leaflets 1.1–1.9 cm wide; inflorescences 2.4–6.7 cm long	P.occidentalis
–	Lateral leaflets 2–3 pairs; leaflets 1.6–2.1 cm wide; inflorescences 8.6–9.7 cm long	P.weberbaueri
63	Lower leaflet surface hairs 0.7–0.9 mm long; inflorescences (6.0–)7.3–10.5(–12.3) cm long, with 11–19 flowers; north-eastern Colombia	P.quadrijuga
–	Lower leaflet surface hairs 0.6–1.5 cm long; inflorescences (2.3–)4.3–13.8 cm long, with 5–9 flowers; Ecuador	P.reticulata