Buddleja diffusa is a species endemic to central Peru and northern Argentina, growing on dry hillsides above rivers and creeks at altitudes of 1000 - 1900 m; it was first described and named by Ruiz and Pavon in 1798.[1] [2]
Buddleja diffusa is a dioecious, scrambling, vine-like shrub 1 - 3.5 m high, with yellowish bark. The young branches are quadrangular, the younger growth covered with a white to buff tomentum. The sessile, membranaceous ovate or elliptic leaves 3 - 14 cm long by 2 - 8 cm wide, glabrescent above, tomentose below. The yellow inflorescences are 15 - 30 cm long, with one or two orders of branches; the flowers borne in capitate cymules, each 0.6 - 1 cm diameter, with 9 - 15 flowers; the corolla tubes are 3 - 3.5 mm long.[2]
The shrub is not known to be in cultivation.