Definition
*Capsella* is a genus of flowering plants in the mustard family, Brassicaceae. It's like that ubiquitous character actor in a movie – not always the star, but always present in the ensemble. The most well-known species is *Capsella bursa-pastoris*, commonly called shepherd's-purse. These plants are often found in disturbed areas and are considered weeds by some, but they play an important role in ecosystems.