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 alabamense
Rhododendron alabamense is found most commonly in Alabama. It can also be found in southern Tennessee, east Georgia, the panhandle of Florida, and eastern Mississippi. This is not a common species, despite its range. It can be found in moist places that are sandy and flat. It is also found in steep, dry areas, like bluffs. The flowers can smell musky or sweet, and lemony. The flowers are white, white with a yellow patch, or light pink. They are sticky due to glandular and non-glandular hairs on the floral tubes. The leaves are dull to slightly glossy, and dark to medium green. The flowers are produced from April into early June.
Rhododendron arborescens
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.
Rhododendron atlanticum
Rhododendron atlanticum, the dwarf azalea, grows on the coastal plain from Georgia to Delaware. It can be found up to 200 miles away from the coast, if the region is sandy, swampy, or dry. These plants can spread by rhizomes if the soil is loose. The flowers can be white or a light pink color, and are fragrant. The flower tubes are the same colors, and are glandular. The pinkish red glands form a line onto each petal tip. Leaf color ranges from gray-green to blue-green. Dwarf azaleas are commonly less than two feet tall. They bloom in the months April and May.
Rhododendron austrinum
Rhododendron austrinum is also called the Florida azalea. It is closely related to R. canescens, and it can be difficult to tell the two apart. It is found in the panhandle of Florida, and the southern regions of Georgia, Alabama, and Mississippi. It has become a popular species in North America because it is easy to grow, is very colorful, and also early to bloom. The flowers range between yellow, orange, and gold. The tubes are a pink/red. The pink color may be a hybrid between this azalea and R. canescens. The stems, leaves, and tubes are glandular. They can grow up to 15 feet and grow well in the sand, and heat. They bloom from March to April.
Rhododendron calendulaceum
Rhododendron calendulaceum is commonly called the flame azalea for its bright yellow, orange, or red color. It is considered to be a very attractive species that people associate with the Appalachian Mountains. It grows from 800 to 6,000 feet elevation ranging from the Piedmont to the Mountains. It can grow up to 12 feet in length. The flowers are 2-3 inches in width. The flower tubes are glandular. This azalea blooms from April to July.
Rhododendron canescens
Rhododendron canescens also has the common names Piedmont Azalea, Southern Pinxter Azalea, and Wild Azalea. It grows in areas where swamps, pocosins, and savannas are present. R. canescens grows in northeast North Carolina, north Tennessee, southeastern Kentucky, southern Illinois, eastern Oklahoma, southern Arkansas, the peninsula of Florida, and southeast Texas. It blooms early March to May.