The Tree Rhododendron is a magnificent flowering tree from Asia that has large, bright red clusters of flowers and evergreen leaves. It is a shrub or a tree and in the wild, it can grow up to 100 feet in height, making it the largest of the rhododendrons. It has dark green, elliptic leaves with silvery or brown lower surfaces. The flowers are red, pink or white. Occurs in forest, thickets and on slopes. It is grown in woodland gardens. It is the national flower of Nepal. Hardy in zones 6-9.