Gillyflower is a common name for Matthiola incana, a plant in the family Brassicaceae (formerly Cruciferae), now more widely known as stock, garden stock or hoary stock, etc.
It is a popular garden flower, which comes in many colors (pink, white or near-white, lavender, yellow…), plain or variegated. Gillyflowers are often used in flowerbeds along paths and alleys, where passers-by can enjoy their pleasant and sweet scent. They can also be grown for cut flowers.
Gillyflowers usually reach a height of about 12 in. (0.30 m) to about 18 in. (0.45 m), although some cultivars can grow up to 28 in. (0.70 m) or more.
The caption reads in the original French:
Giroflée des jardins (Mathiola incana) [sic].