Viola:

Perennial herbaceous plants, standing 10-30 cm in height, with a width of 20-30 cm, well-tolerant to cold, but dislike high temperatures.

Viola tricolor: A biennial or perennial herb with stems reaching 10-40cm in height. The entire plant is smooth and moderately frost-tolerant, preferring cool conditions, and its flowering is significantly affected by light exposure.

Difference in stems: Viola stems are shorter and upright, with good branching ability, quadrangular, with young stems green and older stems often purple-green; Tri-color Viola stems are thicker, either upright or slightly inclined, with ridges, and can be single or multi-branched.

The Differences: Viola leaves are alternate, lanceolate or ovate, with serrations, small stipules that are leaf-like, free, and have petioles; Tri-color Viola has basal leaves that are long ovate or lanceolate, with long petioles, and stem leaves that are ovate, broadly ovate, or lanceolate.

Differences in Flowers: Viola flowers are bisexual, bilaterally symmetrical, with peduncles腋borne, growing about 5-6 cm long, featuring 2 small bracts, a rich array of colors including red, white, yellow, purple, and blue, often with spots; the petals may be of different colors. The pansy flowers are larger, with a diameter of about 3.5-6 cm, with 3-10 blooms on each stem, the peduncles slightly thicker, solitary in the axils of leaves, with 2 opposite bracts at the top, usually in shades of purple, white, and yellow.

The Distinction of the Fruit: Viola fruit is characterized by a more regular ellipsoid shape, splitting into three lobes upon ripening; the fruit valves are boat-shaped. Tri-color Viola fruit is also ellipsoid, measuring 8-12mm in length, and is hairless.

Differences in Growth Habits: Viola tricolor is more cold-resistant than Viola cornuta, while Viola cornuta is more heat-tolerant. Viola tricolor is also more sensitive to the length of daylight compared to Viola cornuta.