1Stipules, 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.
2Style 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.
3Flowers 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).
4Stems or stolons absent.
4'Well-developed decumbent or ascending stems or stolons.
5Spur 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.
6Calycine 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.
7Leaves 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.
8Style filiform.
8'Style clavate.
9Spur at least 3 mm.
9'Spur up to 2½ nim.
10Stipules 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.
11Leaves 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.
12Leaves 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).
13Style 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.
14Leaves with hairs on upperside confined to zone towards margins, glabrous in central portion.
14'Leaves glabrous or, if hairy, hairs not distributed as above.
15Leaves ± 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.
16Petiole 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.
17Style not or slightly marginate at apex.
17'Style distinctly marginate at apex.
18Leaves 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.
19Lateral petals not bearded.
19'Lateral petals bearded.
20Sepals 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.