A former name for a euphorbiaceous genus (Hevea) of South American trees, the principal source of caoutchouc.

Siphonia ("Siphon") was a genus of extinct hallirhoid demosponges of the Upper Cretaceous. They lived in the Western Tethys Ocean, in what is now Europe. They all had distinctive pear-shaped bodies that were attached to the seafloor via a long stem.