Violas, violets, violettas, pansies and heartseases.

Closely related Viola species hybridise easily and hundreds of hybrid cultivars have been created over the centuries.
Virtually all of the Violas seen in gardens are hybrids mostly of Viola cornuta, Viola odorata and Viola tricolor.
In horticulture Viola hybrids are divided into groups based on their morphology.

Violet or viola.
These are small perennial plants with stolons.
They are small ground covers up to 15 or 20 cm high and 100 cms wide.
Flowers have 2 petals that point upwards and 3 downwards.
They are commonly white, blue or purple but are also seen in yellow and orange.
The fragrant flowers may be of 1 or more colours.
The petals lack the ‘faces’ seen in pansies.

Heartsease or Heart’s ease.
These are Viola tricolor and its many cultivars.

Known as Viola x wittrockiana they are hybrids of at least 3 species including V. tricolor.
They are also seen as Viola wittrockiana, Viola hortensis, Viola hortensis hort. and Viola tricolor var. hortensis.

These are larger plants than the violets being up to 30 cm high with larger leaves.
They have fewer flowers but these are larger and often multi-coloured.
Four of the petals point upwards and the lip points downwards.
Flower colours include violet, blue, yellow, orange, red, pink and a deep blackish-purple as well as white.
They have ‘faces’ with lines or central blotches and some have ruffled petals.

Most new Viola cultivars are now pansies that are commonly used as bedding plants.
They are released in ‘Series’ such as the Nature, Crown, Majestic Giant (10 cm wide flowers), Joker and
    the Delta series said to come in 32 colours.

These horticultural types all hybridise between each other so the features used to differentiate them into
    groups may become less obvious.

Two other groups recognised by Viola enthusiasts are Violettas whose petals have no ray markings and Panolas.
There are over 150 cultivars currently available although some only grow in a particular climate.