Polylepis sect. Sericeae, Boza

Key to differentiate the species of the genus Polylepis sect. Sericeae , based on Boza Espinoza & Kessler (2022)

1 Leaflets 0.9–1.1 × 0.4–0.6 cm; inflorescences 0.9–1.0 cm long, with 1 flower................................................... P. rodolfo-vasquezii

- Leaflets (0.8–) 1.1–5.4 × 0.2–2.0 cm long; inflorescences 2.4–36.0 cm long, with (3)4–83 flowers................................................2

2 Leaflets (2.7–)3.4–4.5(–5.4) × (0.6–) 0.8–1.4 cm long, rachis lanuginose to densely lanuginose .....................................................3

- Leaflets (0.8–)0.9–2.4(–3.5) × (0.2–) 0.4–1.4 cm long, rachis glabrous or sparsely sericeous to densely sericeous, villous, or tomentose............................................................................................................................................................................................4

3 Leaflets with 1 pair, obovate to obovate elliptic or oblong elliptic, entire margin with emarginated apices.....................................5

- Leaflets with 5–7 pairs of elliptical, serrate margins with obtuse apices ......................................................................... P. multijuga

4 Abaxial leaflet surfaces sparsely or densely sericeous.......................................................................................................................6

- Abaxial leaflet surfaces are densely lanate or villous ........................................................................................................................7

5 Leaflets 3.0–4.5 × 0.8–1.3 cm long, emarginated apices ............................................................................................. P. rocio-rojasii

- Leaflets (2.7)3.4–4.5(–4.7) × (0.6) 0.8–1.0 cm long, tridentate apices............................................................................... P. yanesha

6 Leaflet margin entire or serrate ..........................................................................................................................................................8

- Leaflet margin slightly crenate ...........................................................................................................................................................9

7 Leaflets with margin entire slightly crenate to serrate .....................................................................................................................10

- Leaflets with margin crenate ............................................................................................................................................................11

8 Abaxial leaflet surface trichomes (1.3–)1.5–1.7(–2.5) mm long .....................................................................................................12

- Abaxial leaflet surface trichomes 0.2–0.9 mm long.........................................................................................................................13

9 Lateral leaflet, 3–4 pairs...................................................................................................................................................................14

- Lateral leaflet, 4–7 pairs...................................................................................................................................................................15

10 Leaflet margin entire to slightly crenate......................................................................................................................... P. longipilosa

- Leaflet margins serrate .....................................................................................................................................................................16

11 Leaflets elliptic; adaxial leaflet surfaces sparsely lanate, trichomes 1.5–2.5 mm long.................................................. P. lanuginosa

- Leaflets ovate to obovate; adaxial leaflet surfaces sparsely sericeous to densely sericeous, trichomes 0.2–1.7 mm long..............17

12 Leaflets obovate (2.4–)3.4–3.9 × (0.8–) 1.1–1.5 cm long with a margin entire to slightly serrate with 12–17(26) flowers ................ ................................................................................................................................................................................................. P. canoi

- Leaflets oblong lanceolate 2.3–4.9 × 0.4–1.0 cm long, margin entire with 8–13 flowers ........................................... P. pampabella

13 Leaflets broadly obovate; adaxial leaflet surfaces with few trichomes on the mid-vein ................................................... P. loxensis

- Leaflets narrowly elliptic to elliptic; adaxial leaflet surfaces glabrous.............................................................................. P. albicans

14 Leaflets with slightly crenate at the apex; inflorescences 3.9–6.6(–7.8) cm long, with 18–21 flowers ............................ P. albicans

- Leaflet margins entire; inflorescences 13.0–17.9(–20.4) cm long, with 23–29 flowers; central ................................... P. humboldtii

15 Leaflets 1.6–3.0 cm long; margins entire to slightly serrate .............................................................................................. P. ochreata

- Leaflets (1.1–) 1.4–1.6 cm long, margins crenate .................................................................................................................... P. pauta

16 Leaflets, obovate; leaflet apices slightly emarginate; 7–15 flowers per inflorescence ................................................. P. frontinensis

- Leaflets elliptic; leaflet apices acute or obtuse; 16–83 flowers per inflorescence ...........................................................................18

17 Abaxial leaflet surfaces densely sericeous, the trichomes 0.2–1.7 mm long ...................................................................................19

- Abaxial leaflet surfaces sparsely to densely tomentose or villous, the trichomes 0.4–2.3 mm long ...............................................20

18 Leaflets 1.1–2.0 cm wide; leaflet apices obtuse; abaxial 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; abaxial leaflet surfaces densely lanate; inflorescences (7.6–)9.5–13.3(–17.3) cm long, with 16–35 flowers ................................................................................................................................................ P. serrata

19 Leaflets 0.8–1.3 × 0.2–0.7 cm; inflorescences 1.2–1.6(–3.5) cm long, with 3 flowers .......................................................... P. pepei

- Leaflets 1.2–3.9 × 0.4–1.5 cm; inflorescences 3.3–20.4 cm long, with 5–29 flowers.....................................................................21

20 Leaflets with serrate margins, lateral leaflets 3–4(5) pairs; abaxial leaflet surface densely villous ............................. P. frontinensis

- Leaflets with margins slightly crenate at the apex, lateral leaflets 3–4 pairs, abaxial leaflet surfaces densely sericeous. P. albicans

21 Lateral leaflets 3–5 pairs; abaxial leaflet surface trichomes 0.2–0.6 mm long ................................................................................22

- Lateral leaflets 2–3 pairs; abaxial leaflet surface trichomes 0.6–1.0 mm long ................................................................................23

22 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 ................................24

23 Leaflets (1.9–)2.4–2.6 × 0.5–0.7 cm; adaxial leaflet surface sparsely to densely sericeous; inflorescences 7.2–8.1 cm long............ ............................................................................................................................................................................................ P. argentea

- Leaflets 1.8–2.1 × 0.8–1.0 cm; adaxial leaflet surfaces glabrous; inflorescences 3.3–4.5 cm long..................................... P. sericea

24 Leaflets elliptic; leaflet margins are slightly crenate at the apex ....................................................................................... P. albicans

- Leaflets broadly obovate; leaflet margins serrate................................................................................................................ P. loxensis