Heath Dog Violet
- Name also: Heath Violet, Heath Dog-violet, European Heath Dog Violet
- Family: Violet Family – Violaceae
- Growing form: Perennial herb.
- Height: 8–40 cm (3.2-16 in.). Stem leafy, limp–ascending–erect, branched–branchless.
- Flower: Corolla zygomorphic, blue, inner parts white (on rare occasions completely white), approx. 0.7–2.5 cm (0.28–1 in.) wide; petals 5, lowest with greenish-yellowish white spur. Sepals 5. Stamens 5. Gynoecium fused, single-styled. Flowers solitary in axils, nodding.
- Leaves: Alternate, stalked, stipulate. Rosette not present. Blade ovate–narrowly cordate, blunt or short-tapered, with shallowly rounded teeth (crenate), somewhat glabrous, quite shiny, basal notch shallow. Stipules narrowly ovate, sparsely toothed.
- Fruit: 3-valved capsule.
- Habitat: Dry hillsides, dryish meadows, banks, roadsides, open forests, broad-leaved forests, burning and logging sites, forest margins, coastal forest, ridged slopes, coppices, grazing land.
- Flowering time: May–June (ssp. canina); June–July (ssp. ruppii).
Heath dog violet can be divided into two subspecies, which are sometimes regarded as two independent species. The subspecies however breed with one another creating plants that are also able to reproduce, which is why they are regarded as a single species. Heath dog violet can cross-breed with a number of other violets.
Ssp. canina is tufted, with a limp or ascending stem, abundantly branched and small-sized. Its leaf-blades are narrowly cordate, thickish, over twice as long as they are broad, with quite small blue flowers. Ssp. ruppii is clearly larger, and it is erect and almost branchless. Its blades are narrowly cordate, thin, around twice as long as they are broad, and its flowers are large and light purplish. Of the two subspecies, ssp. ruppii is more widely spread. It can be found in ridged forests, forest margins, dryish meadows and along shore banks across almost all of Finland. Ssp. canina is clearly rarer in Finland, and it grows along the south coast and southern parts of Finland’s lakeland region in dry, rocky and sandy meadows and fields.
Heath dog violet can be confused with its relative common dog violet (V. riviniana). The species’ ecologies and habitats are however somewhat different: heath dog violet has adapted to exploit succession where the habitat that is initially open, and it doesn’t like shade; common dog violet thrives better in places that have already become forested. Both species have quite a broad tolerance however so they can even grow side by side and easily cross-breed. Their different preferences regarding habitat and also partly different flowering times have usually kept them separate. Wherever people are disturbing the natural forest by felling trees, bulldozing pasture and building roads, the species have broken their moulds and hybrids have perhaps even begun to marginalize pure stands locally.