Moutarde violette

Chorispora tenella is a species of flowering plant in the mustard family known by several common names, including purple mustard, blue mustard, musk mustard, and crossflower. This mustard is native to parts of Eurasia but is well known in other parts of the world, particularly in temperate regions, as an introduced species and a noxious weed. This is an annual herb reaching a maximum of half a meter in height. It has wavy-edged alternate leaves of lanceolate or oblanceolate shape of up to 8 centimeters long, and glandular hairs are typically observed on most parts of the plant. The four tiny petals of each cruciform flower emerge from a loose tube of sepals and spread into a corolla about a centimeter wide. The flowers are lavender to pale magenta in color, and a field heavily infested with purple mustard can take on a distinct lavender wash. The flowers have a light scent—more noticeable when many individual plants are blooming together in a large area—which is considered unpleasant by some and fragrant by others. The fruits are long upturned cylindrical capsules about 4 centimeters long containing round, reddish-brown seeds that eventually burst from the fruit pods.

Source: Wikipedia