Dicksonia sellowiana, the xaxim, or samambaiaçu or imperial samambaiaçu, is an arborescent fern in the family Dicksoniaceae, native to the tropical and subtropical Americas.

Distribution: The fern is native to Southern Mexico, Central America, and South America.

In the South American Atlantic Forest biome, it is found in: Southeastern Brazil in the states of Minas Gerais, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, and Rio Grande do Sul; in northeast of Argentina within Misiones Province; and in eastern Paraguay.

 Dicksonia sellowiana has an erect and cylindrical caudex, reaching sometimes more than 10 m high, the fronds are bipinnate and 2 m long. Due to illegal extraction, the species is at risk of extinction.

Varieties: Dicksonia sellowiana is variable in its form. Variations are sometimes treated as separate varieties, which include:

• Dicksonia sellowiana var. ghiesbreghtii
• Dicksonia sellowiana var. gigantea
• Dicksonia sellowiana var. karsteniana
• Dicksonia sellowiana var. lobulata