North American azaleas are flowering shrubs in the genus Rhododendron, section Pentanthera, subsection Pentanthera, so named because they all have five stamens.Most are in the United States, with one species found in Canada and one being found in Mexico. North American azaleas are commonly confused with azaleas of Asian origin, the evergreen azaleas. North American azaleas are deciduous and produce two types of buds. One is a larger and produces about 20 flowers while the other bud produces a leafy shoot. The flower color, fragrance, and number of stamens vary among species.

Rhododendron arborescens is also called the sweet azalea. It grows from Alabama to Pennsylvania, along the top of wet mountains and near fast moving streams. The flowers can be up to 2 inches wide, white, and commonly have a yellow patch on them. It would be rare to see a light pink color or light yellow. The pistil and the filaments are normally red. This characteristic makes it easy to identify the species. The flowers have white tubes. This azalea is sometimes also called the smooth azalea for its new leaf growth has no hair, making it smooth to the touch. The leaves range from a blue-green, dark green, or a medium green, and the underside is a light white color. The leaves are usually glossy. Its seeds are granular. Plants blooms from May to August.