Definition of water tree
: any of several chiefly tropical plants with fluids that may be used as an emergency source of drinking water: such as
a
: a large Ceylonese pitcher plant (Nepenthes distillatoria)
b
: an African woody vein (Tetracera potatoria) that yields abundant watery sap when a large stem is cut
c
: any of several chiefly arborescent Australian plants (as of the family Proteaceae) that yield a watery sap when the bark or roots are cut;
especially
: a needle wood (Hakea leucoptera) that stores water in its thickened roots
