Rhododendron serrulatum

The native deciduous azaleas of the southeastern United States bloom in sequence from late winter through midsummer — R. canescens in March, the flame azaleas in April and May, R. prunifolium carrying the season into July with its red flowers. And then, when most gardeners have assumed the azalea chapter is finished for the year, Rhododendron serrulatum opens.

August into September. Sometimes later. The flowers are white, narrowly tubular, produced in clusters at the stem tips after the foliage has long since expanded — a timing that makes them easy to overlook in a catalog but impossible to overlook in a garden where the fragrance arrives before the eye does. On a warm, humid afternoon the scent carries considerable distance, sweet and clean in the way of honeysuckle but rounder, more complex. This is not a subtle fragrance note. It is the reason serious native plant collectors consider serrulatum essential to a complete deciduous azalea planting, regardless of how the flowers compare to the showy spring species.

The taxonomy is worth a sentence, since the books do not agree. Some authorities lump Rhododendron serrulatum under R. viscosum as a variety; others maintain it as a distinct species. Woodlanders has long argued for the latter, and the argument holds: the two plants differ in growth habit, flowering time, natural distribution, and several botanical characteristics. R. viscosum blooms in June and July, peaks around eight feet, and favors bogs and wet flatwoods. R. serrulatum blooms in August and September, can reach ten to fifteen feet, and occurs in gallberry thickets, along blackwater streams, and at the edges of sinkhole hammocks — the kind of slightly elevated ground in a wetland landscape that Floridians call a hammock, which is where the common name comes from. They are related, but they are not the same plant, and growing both is the point.

Rhododendron serrulatum ranges farther south than any other native deciduous azalea, extending deep into central Florida where few of its relatives follow. It is the closer of the two to this latitude, more adapted to the heat and humidity of the Deep South, and in the right site — moist, acidic, with some shade and reliable summer moisture — it performs accordingly.