11. Exochorda Lindl. (pearlbush)

One or 5 species, Asia; cultivated widely in temperate regions.

Exochorda usually is treated as comprising four or five closely related species, but in her unpublished dissertation, Gao (1998) presented anatomical, morphological, cytological, and genetic evidence for an alternative classification involving a single species (E. racemosa) consisting of three subspecies. As her subspecific combinations remain unpublished, this treatment has not been adopted elsewhere.

Exochorda species are sometimes cultivated as ornamentals. although they are extremely showy when in flower, their flowering period tends to be rather short. Plants that are not pruned also tend to become leggy, with arching stems. The most commonly cultivated taxon, E. racemosa, escapes sporadically, but does not appear to be sufficiently aggressive in nature to pose an invasive threat.