Hydrangea, also called hortensia, is a genus of flowering plants native to Asia and America. The genus contains approximately 75 species, with more added as hybridizers work to create new colors of flowers and foliage. Hydrangeas are grown for their large, showy flowers, which are actually collections of small fertile and infertile flowers gathered into one large group. A particular species is used in Korea to brew tea. Many different forms are available include bush, climbing, oak leaf and more.