Viola is the largest genus in the Violet family, containing between 525 and 600 annual or perennial plants and a few small shrubs. They are widely distributed over both the Northern and Southern temperate zones. There are also a handful of shrubby species in the Andes, Sandwich Island and in Eastern Europe.
Because Viola freely hybridize, however, it is often difficult to identify their species. The flower, variable in color, but not red, usually grows singly on a stalk and has 5 petals, 4 arranged in unlike pairs, the fifth with a spur. The leaves may grow on the same stalk as the flower (stemmed violets) or on separate stalks (stemless violets). Though the best-known Viola have heart-shaped leaves, the leaves of other species may have different shapes.
Typically, Violas grow in meadows or damp woods. All wild species bloom early in the spring, but some cultivated varieties bloom later. Many species have 2 types of flowers. One type is showy and appears in the spring but often does not produce seeds in some species. The fertile, less conspicuous flower appears in the early summer and is completely closed and self-fertilizing.
Many of the high Andean species are known as Rosulate Violas. They are a group of perennial Violas in which the leaves form a tight rosette, rather like Sempervivum or some of the Saxifrages. However, the flowers appear at leaf level in rings around the outside of the rosette.
Growing Conditions for Rosulate Violas
Wide habitat requirements are found in Viola genus from cool temperate moist woodland to hot, dry stony slopes on tropical mountains. The easy, small hardy species grow well on the rock garden, others need the sharper drainage of a scree or a moisture-retentive humus-rich rooting medium. Yet others require alpine house protection from excessive cold or winter wet. Ordinary moist but well drained soil suits most species plus partial shade.
Rosulate Violas are mainly found in Chile and Argentina and grow in relatively bare loose soils, which are often volcanic in origin. Like many plants in such countries they have a long tap root to ensure access to water.
General Care for Rosulate Violas
Rosulate Violas have a reputation for intractability in cultivation, but it is now known that at least some species can be grown to flowering size by skilled growers. Magnificent plants of Viola dasyphylla appear regularly on the show bench.
A main problem is etiolation, elongation of the normally compact rosettes, in the poor light values of the lowland northern temperate zone. Cool conditions, a sparse but adequate diet and as much light as possible are essential. It is known that in any batch of seedlings some individuals will quickly etiolate, others may not. So there is some scope in selecting plants more likely to grow satisfactorily in cultivation.
How to Propagate Rosulate Violas
Rosulate Violas are grown only from seed and with some patience.
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