Identification key to species of Oxalis sect. Polymorphae

(species with * are here segregated from O. polymopha s. lat. but should be excluded from the section)

1. Leaves arranged along the stem (Fig. 7A), sometimes more densely so at stem apex, but not forming a single terminal pseudo-whorl ......................................................................................................... 2

– Leaves densely grouped at stem apex, forming a single terminal pseudo-whorl (Fig. 14S, Y) or multiple pseudo-whorls .................................................................................................................. 10

2. Pedicel and sepals with glandular hairs (Fig. 7H); sometimes rare and diminute ............................ 3

– Pedicel and sepals without glandular hairs ....................................................................................... 5

3. Leaflet blades with obtuse, rounded or slightly retuse apex ................................ O. alstonii Lourteig

– Leaflet blades with acute, acuminate or caudate apex ...................................................................... 4

4. Inflorescences longer than the petiole of adjacent leaves, dichasial branches> 5 mm long, with flowers arranged distally to a long sterile portion; leaflet blades glabrous, with occasional marginal hairs .. .................................................................................... O. pardoensis (Lourteig) T.S.Costa & Fiaschi

– Inflorescences shorter than the petiole of adjacent leaves, dichasial branches 1.5–4 mm long, with flowers densely grouped along the entire length; leaflet blades glabrescent adaxially, with moderate, patent to appressed hairs abaxially ..................................................... O. animarum Fiaschi sp. nov.

5. Inflorescences mostly cauliflorous (Fig. 10F), not observable in young plants with poorly developed stem ................................................................................................................................................... 6

– Inflorescences mostly axillary (Fig. 6A), but sometimes with a few cauliflorous ones ................... 7

6. Fruits with carpels distally prolonged ca 2 mm long, slightly longer than the sepals (Fig. 8L); leaf blades pubescent; flowers with yellow petals (Fig. 8K); inflorescences usually with bifid dichasial branches (Fig. 8I) ................................................................................................. O. decipiens Progel

– Fruits with carpels not prolonged (Fig. 10K–L) or distally prolonged up to ca 0.5 mm of their length, shorter than the sepals; leaf blades glabrous; flowers with white petals (Fig. 10J); inflorescences with entire dichasial branches (Fig. 10H) .......................................................... O. idimae Fiaschi sp. nov.

7. Leaflet blades with obtuse, rounded or slightly retuse apex ................................ O. alstonii Lourteig

– Leaflet blades with acute, acuminate or caudate apex ...................................................................... 8

8. Flowers with white to pinkish corolla lobes ...................................... O. polymorpha Mart. ex Zucc.

– Flowers with yellow corolla lobes .................................................................................................... 9

9. Trinerved leaflets (Fig. 6E); leaflet blades abaxially with abundant, appressed hairs; inflorescence dichasial branches with flowers congested from the base (Fig. 6K) ..... O. amorimii Fiaschi sp. nov.

– Pinnately-nerved leaflets (Fig. 1C); leaflet blades abaxially glabrous, with occasional hairs along the margin; inflorescence dichasial branches with flowers not congested or, if congested, after a sterile portion (Fig. 1A) ........................................................ O. pardoensis (Lourteig) T.S.Costa & Fiaschi

10. Flower and fruit pedicel glabrous, sometimes with sparse, appressed hairs in bud ........................11

– Flower and fruit pedicel with sparse to very abundant, appressed, curved or patent hairs ............ 14

11. Petioles with intermixed unicelular and pluricelular hairs; mature inflorescences with short dichasial branches (0.5–3 mm long) and flowers (or persistent floral bracts) distributed along the entire length ........................................................................... O. cipoensis T.S.Costa, Sakuragui & Fiaschi

– Petioles glabrous or only with unicelular hairs; mature inflorescences usually with elongated dichasial branches (3.5–17 mm long) and flowers (or persistent floral bracts) distally congested ............... 12

12. Terminal leaflet blade 8–10.5 × ca 2 mm, narrowly elliptic to narrowly oblong or slightly oblanceolate; young stem glabrous; floral bracts glabrous; flowers with yellow corolla lobes ................................ ......................................................................................................................... O. artemioides Fiaschi

– Terminal leaflet blade 10–66 × 5–38 mm, ovate to lanceolate or elliptic to narrowly elliptic; young stem with moderate to very abundant, appressed or curved hairs; floral bracts with sparse, appressed hairs; flowers with white corolla lobes ........................................................................................... 13

13. Leaves grouped in a single, terminal pseudo-whorl; habit unbranched, 10–40 cm tall; terminal leaflet blade 20–66 × 17–38 mm, the base obtuse to rounded or slightly cordate ... O. colatinensis Fiaschi

– Leaves grouped in multiple pseudo-whorls; habit branched, (20–) 50–200 cm tall; terminal leaflet blade 10–20(–30) × 5–13 mm, the base cuneate to obtuse ................................... O. blackii Lourteig

14. Young stem with abundant to very abundant, appressed-retrorse hairs ..... O. umbraticola A.St.-Hil.

– Young stem with sparse to very abundant, appressed, curved or patent hairs, sometimes intermixed with glandular, pluricellular hairs, or glabrescent .......................................................................... 15

15. Peduncle and/or pedicels with intermixed unicelular and glandular-pluricelular hairs, or only with glandular hairs ................................................................................................................................ 16

– Peduncle and pedicels usually only with unicelular hairs, sometimes with few intermixed glandular hairs ................................................................................................................................................. 17

16. Lateral leaflets with symmetric to slightly asymmetric blades, similar to the terminal leaflet blade; petiole longer than the terminal leaflet blade ................................................... O. kollmannii Fiaschi

– Lateral leaflets with strongly asymmetric blades, diferente from the terminal leaflet blade; petiole usually shorter than the terminal leaflet blade ...................................................... O. neuwiedii Zucc.

17. Leaflet blades glabrous or glabrescent on both surfaces ................................................................ 18

– Leaflet blades with sparse to abundant hairs abaxially, glabrescent or with sparse hairs adaxially ... ......................................................................................................................................................... 20

18. Petioles as long as or longer than terminal leaflet blade; leaflet blades with obtuse, rounded or slightly retuse apex; corolla ≤ 10 mm wide ...................................................................... O. alstonii Lourteig

– Petioles usually shorter than terminal leaflet blade; leaflet blades with acute to acuminate apex; corolla ≥ 15 mm wide .................................................................................................................................. 19

19. Terminal leaflet blade ≥2 × longer than the lateral blades (Fig. 11B), with 5 –7 pairs of secondary veins; blade margins plane, ciliate. Pedicels with abundant, short, retrorse hairs; peduncles 9–50 mm long ..................................................................................................... O. itatingae Fiaschi sp. nov. *

– Terminal leaflet blade up to ca 1.5 × longer than the lateral blades (Fig. 13C, D), with 9–12 pairs of secondary veins; blade margin plane to revolute, with the occasional hairs usually hiding under the margin. Pedicels with sparse to moderate, curved to appressed, antrorse hairs; peduncles 82–110 mm long .................................................................... O. tijucana (Lourteig) Fiaschi comb. et stat. nov. *

20. Terminal leaflet apex acute or acuminate; lateral leaflets strongly asymmetric ............................. 21

– Terminal leaflet apex obtuse or rounded, sometimes acute; lateral leaflets symmetric or slightly asymmetric ....................................................................................................................... O. puberula

21. Flowers with white to pinkish corolla lobes; leaflet blades adaxial surface usually glabrescent ....... ............................................................................................................ O. polymorpha Mart. ex Zucc.

– Flowers with yellow corolla lobes; leaflet blades adaxial surface with moderate, appressed hairs ... ........................................................................................................................... O. roselata A.St.-Hil.