Buddleja thyrsoides is a lowland species endemic from southern Paraguay to the deltas of the Río de la Plata and Paraná River in Brazil, Argentina and Uruguay.[1] The species was first described and named by Lamarck in 1792.[2]
Buddleja thyrsoides is a dioecious shrub 1 - 3. m tall, with tan bark, the young branches covered with white tomentum. The leaves are sessile or subsessile, linear or linear-lanceolate, the blade 7 - 15 cm long by 0.4 - 3 cm wide, subcoriaceous, glabrescent above, and white tomentose below. The fragrant white leafy inflorescences are 5 - 15 cm long by 2 - 3 cm wide, comprising 1 - 2 orders of branches, 0.5 - 2 cm long with cymose clusters of 5 - 15 flowers; the tubular corollas 3 - 4 mm long.[1]
Norman identifies two subspecies distinguished by narrower seeds and denser tomentum resp.:[1]
Neither the species nor its subspecies are known to be in cultivation.