According to the University of Minnesota, over 800 species belong to the azalea and rhododendron genus, making it the largest genera of woody plants. The different types of azaleas vary widely in cold hardiness, sun tolerance, color, size, shape and bloom dates. Azaleas grow into a compact, flowering shrub that thrives in partial shade. The ideal azalea planting location features filtered sunlight and protection from strong winds, as recommended by gardening website Gardens Ablaze.
Species azaleas consist of azaleas that interbreed when isolated in nature. When planted, the seed of a species azalea will grow into the same plant as the parent. Examples of species azaleas are azaleas native to the United States, including Rhododendron canescens, Rhododendron eastmannii and Rhododendron viscosum.
Hybrid azaleas are crosses between different species or other hybrids. When planted from seed, the resulting plant does not resemble the parent plant. The only way to truly reproduce a hybrid is from cuttings. Hybrid groups include the aromi, the glenn dale and the robin hill. The Japanese have hybridized satsuki azaleas for at least 500 years, according to the Azalea Society of America website.
All native North American azaleas are deciduous in nature. In the fall, they shed their leaves. Flower colors for deciduous azaleas include purple, pink, red, white, orange and yellow. Rhododendron austrinum features fragrant yellow blooms, while Rhododendron perclymenoides features a more traditional pink bloom.
Evergreen azaleas in North America are native to Japan. The evergreen azalea retains foliage throughout the fall and winter months. Bloom colors include white, pink, purple, red and orange. Evergreen azaleas include the satsuki group, the sonoma dwarf group and the back acres group of hybrid azaleas.
A wide array of flower types are found among the different types of azaleas. The four classifications of flower type are single, hose-in-hose, double and double hose-in-hose. A single flower features five to six petals around five stamens and one pistil, such as in the Kobai azalea. Hose-in-hose refers to azaleas featuring 10 to 12 petals, which includes the calyx. A double azalea features stamens that become petals, leading to a variable number of petals. Double hose-in-hose azaleas feature over 30 petals, exemplified by the azalea Balsaminiflorum.
Different petal shapes also transform the look of the azalea. The Azalea Society of America points out that azalea flowers range in size from a half inch to over five inches, featuring pointed, triangular or rounded petals.