Erben, M. 1985: Cytotaxonomische Untersuchungen an südosteuropäischen Viola-Arten der Sektion Melanium. – Mitt. Bot. Staatssamml. München 21: 339-740Meikle, R.D. 1977: Flora of Cyprus 1
but supplemented and accepted names differing. The key needs further testing, especially regarding the last two species and their characters.
1Perennial species; leaves cordate
1'Annuals; leaves not cordate
2Sepals acute; plant glabrous; flowers scentless; stipules not membranous
2'Sepals obtuse; plants more or less pubescent; flowers scented; stipules membranous
3Stipules ovate or ovate-lanceolate, shortly glandular-fimbriate; stolons rooting at tip
3'Stipules linear-lanceolate with long-ciliate margins; stolons not (or tardily) rooting at tip
4Stipules with foliaceous mid-lobe and several palmately arranged lateral lobes; leaves usually crenate-serrate
4'Stipules not foliaceous, with a few irregular lateral lobes or none
5Sepals ovate; mid-lobe of stipule not stipitate; plant usually distinctly villose, hairs 0.5-2 mm long
5'Sepals narrowly oblong; mid-lobe of stipule usually with a slender stipe; plant subglabrous or sparsely puberulous, hairs 0.3-0.8 mm long
6Flowers with yellowish and white parts; stipules entire
6'Flowers predominantly with lilac-blue parts; stipules with 1-2 small teeth