Astianthus is a monotypic genus of flowering plants in the Bignoniaceae family. The sole species is Astianthus viminalis. It is known by the common names achuchil in Mexico and chilca in Guatemala and Honduras.

Astianthus is native to Mesoamerica, from southern Mexico to Nicaragua. It is a shrub, or if larger, a tree of varying height, occurring mostly along streambanks from sea level to 1,200 m (3,900 ft) in elevation. Its leaves are unusually long and slender, resembling those of a willow, possibly because it is a rheophyte.

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