Identification key for the native species of Pleroma in the state of Paraná (adapted from Meyer et al. 2010a).

1. Flowers solitary ................................................................................................................................................................................. 2

- Flowers arranged in inflorescences, from cymes with few flowers (3–7 flowers) to thyrsoids with more than 15 flowers ........... 4

2. Shrubs; leaves with the adaxial surface glabrous..................................................................................................... P. setosociliatum

- Trees; leaves with the adaxial surface covered by indumentum ...................................................................................................... 3

3. Leaves with three main veins; style glabrous ............................................................................................................. P. sellowianum

- Leaves with five main veins; style pilose ..................................................................................................................... P. raddianum

4. Branches, leaves (both surfaces), and hypanthium covered with eglandular, dendritic or stellate trichomes ................................. 5

- Branches, leaves (both surfaces), and hypanthium covered with glandular or eglandular trichomes, these devoid of lateral ramifications ..................................................................................................................................................................................... 6

5. Leaves slightly discolorous; young branches, petioles, and inflorescence branches covered with dendritic trichomes; antesepalous stamens with pedoconnective appendages 0.9–1.2 mm long ......................................................................................... P. joelsilvae

- Leaves strongly discolorous; young branches, petioles, and inflorescence branches covered with stellate trichomes; antesepalous stamens with pedoconnective appendages 1.5–3 mm long ............................................................................................ P. oleifolium

6. Anthers with a truncate apex ........................................................................................................................................... P. hospitum

- Anthers with an attenuate apex.......................................................................................................................................................... 7

7. Leaves strongly discolorous, distinctly whitish on the abaxial surface ............................................................................................ 8

- Leaves concolorous or slightly discolorous, not whitish on the abaxial surface .............................................................................. 9

8. Leaves with the adaxial surface covered by glandular trichomes; petals purple .................................................................. P. molle

- Leaves with the adaxial surface covered by eglandular trichomes; petals white ............................................................... P. dusenii

9. Leaves whorled on proximal branches, opposite on distal branches ............................................................................. P. frigidulum

- Leaves always opposite, both on proximal and distal branches ..................................................................................................... 10

10. Bracteoles six, persistent at the base of the hypanthium in mature flowers .............................................................. P. hatschbachii

- Bracteoles two, early deciduous ..................................................................................................................................................... 11

11. Anthers white...................................................................................................................................................................... P. ursinum

- Anthers purple to lilac .................................................................................................................................................................... 12

12. Hypanthium sericeous .................................................................................................................................................................... 13

- Hypanthium setose or strigose ........................................................................................................................................................ 17

13. Trees; flowers 7–8 cm in diameter ................................................................................................................................... P. caissara

- Shrubs; flowers 3.5–6 cm in diameter ............................................................................................................................................ 14

14. Leaves sessile or with very short petioles, less than 2 mm long; blade apex obtuse ...................................................... P. clavatum

- Leaves with petioles longer than 3.8 mm long; blade apex acute .................................................................................................. 15

15. Leaves strigose on the adaxial surface; sepals ca. 10 mm long ................................................................................. P. goldenbergii

- Leaves sericeous on the adaxial surface; sepals 5.5–7.5 mm long ................................................................................................. 16

16. Bracteoles 9.4–10.5 × 5.7–6.7 mm; plants occurring in Paraná’s coastal region ....................................................... P. urvilleanum

- Bracteoles 6.4–7.2 × 3.9 mm; plants occurring on Paraná’s highlands ..................................................................... P. guartelaense

17. Filaments villose, with trichomes 1–3 mm long .............................................................................................................. P. martiale

- Filaments glabrous or puberulous, setose, setulose, with trichomes 0.2–0.5 mm long. ................................................................. 18

18. Leaves with the adaxial surface covered by trichomes distributed in longitudinal bands along the space between the veins ........... ............................................................................................................................................................................................. P. dubium

- Leaves with the adaxial surface covered with trichomes distributed over the entire surface ........................................................ 19

19. Bracteoles 4–7.5 mm long .............................................................................................................................................................. 20

- Bracteoles 10–20 mm long ............................................................................................................................................................. 21

20. Leaves elliptic, with 5 veins; plants occurring in Paraná’s coastal plain .................................................................. P. trichopodum

- Leaves ovate to ovate-lanceolate, with 7 veins; plants occurring in Paraná’s highlands ..................................................... P. kleinii

21. Branches hirsute; leaves with reticulation visible on the abaxial surface with reticulate veins; bracteoles ovate ............ P. pilosum

- Branches strigose; leaves with reticulation not visible on the abaxial surface; bracteoles orbiculate .................................. P. reitzii