In horticulture, the term pansy is normally used for those multi-colored large-flowered cultivars which are raised annually or biennially from seed and used extensively in bedding.

Annual or perennial caulescent or acaulescent (with or without a visible plant stem above the ground) herbs, shrubs or very rarely treelets.

The flowers of the vast majority of the species are strongly zygomorphic with bilateral symmetry and solitary, but occasionally form cymes.

[2] After flowering, fruit capsules are produced that are thick walled, with few to many seeds per carpel, and dehisce (split open) by way of three valves.

[4] The nutlike seeds, which are obovoid to globose, are typically arillate (with a specialized outgrowth) and have straight embryos, flat cotyledons, and soft fleshy endosperm that is oily.

[10] However, in 1802 Batsch had already established a separate family, which he called Violariae based on Viola as the type genus, with seven other genera.

[21] The extensive taxonomic studies of Wilhelm Becker, culminating in his 1925 conspectus, resulted in 14 sections and many infrasectional groups.

Subsequent studies using molecular phylogenetic methods, such as that of Ballard et al. (1998) have shown that many of these traditional divisions are not monophyletic, the problem being related to a high degree of hybridization.

However, the exact phylogenetic relationships remain unresolved, as a consequence many different taxonomic nomenclatures are in use, including groupings referred to as Grex.

[20] Marcussen et al. place the five S American sections, Andinium, Leptidium, Tridens, Rubellium and Chilenium at the base of the phylogenetic tree, in that order.

It occurs at high altitudes (above 600 m) in both N America and northeast Asia, including Siberia and Korea, and the species are perennial, caulous and herbaceous.

[19][20] Habitat fragmentation has been shown to have minimal effect on the genetic diversity and gene flow of the North American woodland violet Viola pubescens.

Plants that produce copious amounts of clonal seeds from cleistogamous flowers often experience increased levels of inbreeding.

[55] Many violet seeds exhibit physiological dormancy and require some period of cold stratification to induce germination under ex situ conditions.

[58] In North American habitat restoration, native violets are in high demand due to their relationship with the aforementioned fritillary butterflies.

[59] Violet species occupy a diverse array of habitats, from bogs (Viola lanceolata) to dry hill prairies (V. pedata) to woodland understories (V. labradorica).

While many of these species are indicators of high quality habitat, some violets are capable of thriving in a human altered landscape.

Two species of zinc violet (V. calaminaria and V. guestphalica) are capable of living in soils severely contaminated with heavy metals.

[a][62] The international registration authority for the genus is the American Violet Society, where growers register new Viola cultivars.

[63] A coding system is used for cultivar description of ten horticultural divisions, such as Violet (Vt) and Violetta (Vtta).

[66] In this system violets (Vt) are defined as "stoloniferous perennials with small, highly fragrant, self-coloured purple, blue or white flowers in late winter and early spring".

In horticulture the term pansy is normally used for those multi-colored, large-flowered cultivars which are raised annually or biennially from seed and used extensively in bedding.

[63] The following cultivars, of mixed or uncertain parentage, have gained the Royal Horticultural Society's Award of Garden Merit:[71] Other popular examples include:[79]

The heart-shaped leaves of V. odorata provide a free source of greens throughout a long growing season,[80] while the petals are used for fragrant flavoring in milk puddings and ice cream or in salads and as garnishes.

A double blind clinical trial showed that the adjuvant use of Viola odorata syrup with short-acting β-agonists can improve the cough suppression in children with asthma.

[89][90] In another study intranasal administration of Viola odorata extract oil showed to be effective in patients with insomnia.

[90] Topical use of an herbal formulation containing Viola tricolor extract also showed promising effects in patients with mild-to-moderate atopic dermatitis.

Ionone is present in the flowers, which turns off the ability for humans to smell the fragrant compound for moments at a time.

[101][102] This connection originates from fragments of a poem by Sappho about a lost love, in which she describes her as "Close by my side you put around yourself [many wreaths] of violets and roses.

"[103] In another poem, Sappho describes her lost love as wearing "violet tiaras, braided rosebuds, dill and crocus twined around" her neck.