Identification Key to the species of Rhynchosia that occur in South America

1. Leaves unifoliolate ................................................................................................................................................ 23. R. platyphylla

- Leaves trifoliolate ..............................................................................................................................................................................2

2. Inflorescence equalling or exceeding the length of the subtending leaf .......................................................................................... 3

- Inflorescence shorter than the length of the subtending leaf ...........................................................................................................21

3. Surface of leaflets bullate; inflorescence corymbiform ............................................................................................. 7. R. corylifolia

- Surface of leaflets not bullate; inflorescence racemose or paniculate .............................................................................................. 4

4. Plant covered with a cinereous indumentum; leaves sessile to subsessile ............................................................ 14. R. leucophylla

- Plant covered with a white or yellow indumentum; leaves petiolate ............................................................................................... 5

5. Calyx with at least one lobe equaling or exceeding the length of the corolla (sometimes slightly shorter on the same specimen in R. lateritia) ...................................................................................................................................................................................... 6

- No calyx lobes exceeding the length of the corolla (sometimes slightly longer on the same specimen in R. burkartii) ............... 11

6. Leaflets narrowly lanceolate to linear .......................................................................................................................... 16. R. lineata

- Leaflets narrowly elliptical to elliptical, oblong, ovate, deltoid to rhombic, obovate or rounded ................................................... 7

7. Inflorescence less than twice the length of the subtending leaf .................................................................................. 2. R. balansae

- Inflorescence often more than twice the length of the subtending leaf ............................................................................................ 8

8. Only the ventral lobe of the calyx exceeding the length of the corolla .............................................................. 26. R. schomburgkii

- All calyx lobes equaling or exceeding the length of the corolla ...................................................................................................... 9

9. Stems prostrate ........................................................................................................................................................... 13. R. lateritia

- Stems twining ................................................................................................................................................................................. 10

10. Stipules 3–10 mm long; leaflets pubescent or tomentose ........................................................................................ 24. R. reticulata

- Stipules 1–2.5 mm long; leaflets puberulous to pilose................................................................................................. 5. R. calycosa

11. Fruit slightly to strongly constricted between seeds; seeds bicolored ............................................................................................ 12

- Fruit without constrictions between seeds; seeds unicolored ......................................................................................................... 15

12. Fruit reddish-brown to black, glabrescent ...................................................................................................................................... 13

- Fruit greenish or brownish, pilose to pubescent ............................................................................................................................. 14

13. Vesicular glands on the abaxial leaflet surface only; stipels present; pedicel 2–4 mm long .............................. 18. R. melanocarpa

- Vesicular glands on both leaflet surfaces; stipels absent; pedicel 1–2 mm long ................................................ 10. R. erythrinoides

14. Fruits slightly constricted between seeds; seeds bicolored, yellow to orange and black .............................................. 15. R. lewisii

- Fruits strongly constricted between seeds; seeds bicolored black and red ......................................................... 22. R. phaseoloides

15. Flowers 35–39 mm long ....................................................................................................................................... 11. R. franciscana

- Flowers up to 18 mm long .............................................................................................................................................................. 16

16. Vesicular glands present on both leaflet surfaces ........................................................................................................................... 17

- Vesicular glands present only on the abaxial leaflet surface .......................................................................................................... 19

17. Fruit falcate .................................................................................................................................................................. 20. R. minima

- Fruit elliptic, oblong, or ovate ........................................................................................................................................................ 18

18. Fruit covered by pubescent to hirsute hairs and bulbous-based trichomes ............................................................... 12. R. hauthalii

- Fruit covered by pilose hairs, bulbous-based trichomes absent .................................................................................. 3. R. burkartii

19. Fruits narrowly obovate, lacking bulbous-based trichomes .......................................................................................... 25. R. rojasii

- Fruits oblong to slightly obovate, densely covered with bulbous-based trichomes........................................................................ 20

20. Vesicular glands on the abaxial leaflet surface brown to black; flowers 5–8 mm long ................................................... 9. R. edulis

- Vesicular glands on the abaxial leaflet surface yellow; flowers 9–13 mm long ................................................ 17. R. mantaroensis

21. Inflorescence racemose .................................................................................................................................................................. 22

- Inflorescence corymbiform or fasciculate ...................................................................................................................................... 23

22. Fruit reddish-brown to black, with constrictions between seeds ......................................................................... 21. R. naineckensis

- Fruit greenish to brownish, without constrictions between seeds ...................................................................... 4. R. caaguazuensis

23. Inflorescence fasciculate ................................................................................................................................................................ 24

- Inflorescence corymbiform ............................................................................................................................................................ 25

24. Fruit falcate ..................................................................................................................................................................... 27. R. senna

- Fruit oblong, obovate, or elliptic ............................................................................................................................. 8. R. diversifolia

25. Plant covered by hirsute hairs; calyx lobes elliptic or narrowly ovate ...................................................................... 6. R. claussenii

- Plant covered by pilose to pubescent hairs; calyx lobes linear or lanceolate ................................................................................. 26

26. Stems prostrate; stipules ovate, 5–10 mm long ........................................................................................................... 19. R. mineira

- Stems erect; stipules lanceolate to triangular, 2–5 mm long ...................................................................................... 1. R. arenicola