Leaves alternate, cauline or radical; lamina ± circular to lanceolate, margins toothed, crenate or ± entire, petiolate; stipules present, usually leafy.
Flowers solitary on axillary scapes with a pair of bracteoles near or below the middle. Sepals produced into small basal appendages. Lower petal spurred or pouched at base, lateral petals often bearded within. Anthers with a flat membranous appendage; the 2 lowest anthers with a spur at the base. Ovary glabrous or hairy; style usually bent.
Species 6–8 are treated here at species level as opposed to their subspecific ranking under V. hederacea, in Adams & George (1982).
| | Key to the species | |
| 1 | Annual or biennial; stipules to 4 cm long, green, deeply lobed; lower petal broad-cuneate | Viola arvensis |
| Perennials; stipules small, often brownish, translucent; lower petal ovate to linear-oblong | 2 |
| 2 | Plants not stoloniferous but stems sometimes elongated and decumbent; lower petal spurred; flowers scentless; styles thickened towards apex | 3 |
| Plants stoloniferous, stems rarely elongated; lower petal shallowly pouched but lacking a spur or if spurred then flowers sweetly scented;style not apically thickened
Back to 1 | 5 |
| 3 | Stems lax, elongated; leaves cauline, lamina heart-shaped | 4 |
| Stems erect, short; leaves radical, lamina lanceolate to oblong, the base cuneate or shallowly cordate
Back to 2 | Viola betonicifolia |
| 4 | Stipules frimbriate; corolla blue violet; uncommon garden escape (recorded only in Central Tablelands in NSW) | Viola riviniana |
| Stipules entire or sparcely toothed; corolla white or rarely pale violet(recorded from coast and tableland regions of NSW)
Back to 3 | Viola caleyana |
| 5 | Petiole with short deflexed hairs, flowers strongly scented; lower petal spurred; capsule hairy | Viola odorata |
| Petiole glabrous, or if hairy the hairs not deflexed; flowers scentless or faintly scented; lower petal not spurred; capsule usually glabrous
Back to 2 | 6 |
| 6 | Flowers mostly discolorous, petals 7–15 mm long | 7 |
| Flowers usually concolourous, petals less than 7 mm long
Back to 5 | 9 |
| 7 | Leaves reniform to semicircular, more often wider than longer; flowers discolourous violet and white | 8 |
| Leaves orbicular with a deep sinus, flowers strongly discolourous, bright violet with prominent white tips
Back to 6 | Viola banksii |
| 8 | Flower colour usually not strongly demarcated (occasionally concolourous pale violet to almost white); anther glands purplish or dull green | Viola hederacea |
| Flower colour strongly demarcated (sometimes sub-concolourous, dark violet and pale violet); anther glands whitish green, never purple
Back to 7 | Viola eminens |
| 9 | Flower scapes exceeding the leaves; flowers pale mauve to white, petals 4–7 mm long | 10 |
| Flower scapes usually shorter than or scarcely exceeding the leaves; flowers blackish violet or cream, petals less than 4 mm long
Back to 6 | 11 |
| 10 | Leaves narrow spathulate usually 2–4 times longer than wider, with the top of the leaf curved; the acute terminal tooth distinctly larger than the lateral teeth | Viola sieberiana |
| Leaves usually reniform usually 1–5 times wider than long; with the top of the leaf almost flat; the central tooth no larger than the lateral teeth
Back to 9 | Viola silicestris |
| 11 | Corolla blackish violet, lower petal c. 2 mm wide, obovate to elliptic | Viola fuscoviolacea |
| Corolla cream, often with a purplish tinge towards the centre; lower petal c. 1 mm wide, linear to oblong
Back to 9 | Viola cleistogamoides |
