Key to the genera of Merianieae in Peru

1. Tiny herbs generally less than 50 cm tall, or occasionally subshrubs up to 1.5 m tall; fruits with mature hypanthia costate with 8–10 evident ribs .........................................................................................................................................................................................2

- Shrubs, vines, or trees more than 1 m tall; fruits with mature hypanthia terete, sometimes slightly angled in Adelobotrys or slightly costate in Meriania (with 10 evident ribs in Meriania sumatika, but in this case trees 5–20 m tall) ................................................3

2. Inflorescences solitary or in pairs; stamen connectives with one dorso-basal appendage................... Macrocentrum (Fig. 1G–1H)

- Inflorescences in unilateral scorpioid cymes with more than 10 flowers (with 1–4 flowers in S. peruviana); stamen connectives with two appendages, one dorso-basal and the other dorsal ............................................................ Salpinga (in Peru) (Fig. 1K–1L)

3. Stamen connectives with two appendages, one dorso-basal and the other dorsal..............................................................................4

- Stamen connectives with only one dorso-basal appendage................................................................................................................5

4. Vines or occasionally shrubs with malpighiaceous trichomes; stamen connectives with bifid ascending dorsal appendages or at least apically bilobed .................................................................................................................................. Adelobotrys (Fig. 1A–1B)

- Shrubs, trees or rarely climbers, glabrous or with various indument types but never with malpighiaceous trichomes; stamen connectives with dentiform dorsal appendages or as mere humps, if it is ascending then blunt, apically sagittate or trilobed .......... ........................................................................................................................................................................ Meriania p.p. (Fig. 1J)

5. Inflorescences erect, pseudo-pendulous or pendulous; stamen from both cycles with evident inflated (bulbous) connectives, except some species with 4-merous flowers but in these cases always with pendulous inflorescences (see comments below Meriania rubriflora)........................................................................................................................................................ Axinaea (Fig. 1C–1D)

- Inflorescences erect (except pendulous in M. rubriflora); stamens from both cycles with connectives not inflated (bulbous) (but antepetalous stamens of Meriania macrophylla complex with connectives inflated)........................................................................6

6. Hypanthia and calyces with various indument types; petals less than 4 mm long, if more than 4 mm long then hypanthia and calyces setose; stamen connectives with dorso-basal appendages always descending; anthers with pores ventrally inclined. .......... ....................................................................................................................... Graffenrieda (including Centronia . s.s.) (Fig. 1E–1F)

- Hypanthia and calyces with various indument types but never setose; petals more than 9.5 mm long; stamen connectives with dorso-basal appendages descending or almost perpendicular to the thecae; anthers with pores dorsally inclined.............................. ......................................................................................................................................................................... Meriania p.p. (Fig. 1I)