What is "exochorda"

Exochorda is a small genus of flowering plants in the family Rosaceae, native to China and central Asia (Turkestan). They are used as ornamental plants with the common name pearl bush, or pearlbush. Numerous species have been described on the basis of differing appearance and geographical separation, but a systematic study revealed that the different types are closely related and probably all descended from a single species that formerly had a wide distribution that has been fragmented by habitat loss. As a single species the correct name is E. racemosa.