Not to be confused with Capsella (bivalve).
Capsella is a genus of herbaceous plant and biennial plants in the mustard family Brassicaceae. It is a close relative of Arabidopsis, Neslia, and Halimolobos.

Some recent authors circumscribe Capsella to contain only three species: Capsella bursa-pastoris, Capsella rubella and Capsella grandiflora.

Capsella rubella is a self-fertilizing species that became self-compatible 50,000 to 100,000 years ago. Its outcrossing progenitor was Capsella grandiflora. In general, the shift from outcrossing to self-fertilization is among the most common transitions in flowering plants. Capsella rubella is studied as a model for understanding the evolution of self-fertilization.

Species

Capsella abscissa
Capsella andreana
Capsella australis
Capsella austriaca
Capsella bursa-pastoris (shepherd's purse)
Capsella divaricata
Capsella draboides
Capsella gracilis
Capsella grandiflora
Capsella humistrata
Capsella hybrida
Capsella hyrcana
Capsella integrifolia
Capsella lycia
Capsella mexicana (syn. Bursa mexicana)
Capsella orientalis
Capsella pillosula
Capsella pubens
Capsella puberula
Capsella rubella (red shepherd’s purse)
Capsella schaffneri (syn. Asta schaffneri)
Capsella stellata
Capsella tasmanica
Capsella thomsoni
Capsella thracica
Capsella viguieri
Capsella villosula

source - Wikipedia