| 1 | Stipules, at least the upper ones, pinnatifid or palmatifid. Style expanded above into a globose head. |
| 1' | Stipules entire to long-fimbriate. Style not as above. |
| 2 | Style hooked at apex to give stigmatic beak about as long as the diameter of the style. Capsule on decumbent peduncle, not explosive. |
| 2' | Style not markedly hooked, stigmatic beak much shorter than the diameter of the style. Capsule on erect peduncle, explosive. |
| 3 | Flowers yellow. Leaves reniform to broadly ovate, apex rounded or obtuse. Stipules entire or sparsely denticulate. Style with apex lobes fused behind, no stigmatic beak. |
| 3' | Flowers purple or white, rarely yellow (sp. 13). |
| 4 | Stems or stolons absent. |
| 4' | Well-developed decumbent or ascending stems or stolons. |
| 5 | Spur 2½-6 mm, 2-4 times as long as wide, generally downwards curving, 2-5 times as long as calycine appendages. |
| 5' | Spur up to 3½ mm, up to 1½ times as long as wide, straight or slightly upcurved, up to 3 times as long as calycine appendages. |
| 6 | Calycine appendages (1-)2-4.8 mm, incised, often conspicuous, ½-¾ (-1) as long as sepal. |
| 6' | Calycine appendages 0-2 (-2½) mm, rounded or subdentate, not conspicuous, up to ⅓ (rarely ½) as long as sepal. |
| 7 | Leaves at least 16 mm, long-decurrent on petiole, glabrous. |
| 7' | Leaves up to 16 mm, not or scarcely decurrent on petiole, with clusters of hairs in marginal dentations on upper side. |
| 8 | Style filiform. |
| 8' | Style clavate. |
| 9 | Spur at least 3 mm. |
| 9' | Spur up to 2½ nim. |
| 10 | Stipules long-fimbriate. Calycine appendages at least 0.8 mm, pointed or denticulate, usually hirsute. |
| 10' | Stipules sparsely fimbrio-dentate. Calycine appendages up to 1 mm, rounded, glabrous. |
| 11 | Leaves and flowers grouped in distinct rosettes at intervals along stolons. Stipules free. |
| 11' | Leaves and flowers not grouped in distinct rosettes. Stipules half-adnate to petiole. |
| 12 | Leaves usually broader than long, arcuate or ovate, usually with prominent upturned basal lobes, crenulate or dentate. |
| 12' | Leaves usually longer than broad, if broader than long then with rounded apex and prominently round-crenate (see V. diffusa). |
| 13 | Style with separate rounded marginal lobes at apex. Stipules usually entire or shortly fimbrio-dentate. |
| 13' | Style with apex having flattened marginal lobes which are fused posteriorally. Stipules long-fimbriate. |
| 14 | Leaves with hairs on upperside confined to zone towards margins, glabrous in central portion. |
| 14' | Leaves glabrous or, if hairy, hairs not distributed as above. |
| 15 | Leaves ± twice or more as long as broad, elliptical to lanceolate-ovate. |
| 15' | Leaves up to 1¾ times as long as broad, suborbicular to ovate or elliptical. |
| 16 | Petiole conspicuously winged. Leaves orbicular to orbicular-ovate, rarely elliptical when base cuneate to subcordate. |
| 16' | Petiole not or scarcely winged. Leaves ovate to triangular-ovate, rarely elliptical when base with narrow deep sinus. |
| 17 | Style not or slightly marginate at apex. |
| 17' | Style distinctly marginate at apex. |
| 18 | Leaves white-hirsute above and beneath, elliptical to ovate. |
| 18' | Leaves glabrous or sparsely hirsute in marginal indentations or on veins, especially below, ovate to triangular-ovate. |
| 19 | Lateral petals not bearded. |
| 19' | Lateral petals bearded. |
| 20 | Sepals at least 4 by 1 mm, margins entire, appendages rounded or denticulate. Leaves subcoriaceous, glabrous or sparsely hirsute on veins towards base. |
| 20' | Sepals c. 3 by 1 mm, margins denticulate, appendages dentate. Leaves herbaceous, sparsely hirsute in crenations. |
