Watercress (Nasturtium officinale) is a plant belonging to the cabbage family.

An excerpt from the article 20 facts about watercress

The cabbage family, once called the cruciferous family, has 343-353 genera and about 3630-4010 species. Brassicas are found on all continents except Antarctica and are not found in dense areas of lowland equatorial forests. Many plants in this family are of great utilitarian importance (vegetable cabbage, cabbage proper, rapeseed, rocket, watercress, and others).