| 1 | Flowers yellow | Oxalis corniculata |
| 1 | Flowers purple, pink, mauve or white (sometimes with a green or yellow centre) | 2 |
| 2 | Flowers solitary | Oxalis obliquifolia |
| 2 | Flowers in pseudo-umbels | 3 |
| 3 | Plant without a vertical rhizome and with bulb or bulbs at or near the surface of the ground at the base of the leaf rosette | Oxalis latifolia |
| 3 | Plant with a vertical rhizome and with the bulb or bulbs some centimetres below the surface of the ground | 4 |
| 4 | Leaflets entire or nearly so (not lobed or notched or conspicuously emarginate) | Oxalis anthelmintica |
| 4 | Leaflets 2-lobed or 2-partite | Oxalis semiloba subsp. semiloba |