Rhododendron viscosum ‘Roseum’

The swamp azalea, Rhododendron viscosum, ordinarily opens white; this selection breaks pink. 'Roseum' is a rose-flushed form of the familiar native, chosen and introduced by Woodlanders from a plant of Aiken County, South Carolina provenance, a home-ground selection that carries the sweet, clove-like fragrance of the species in a warmer color. The swamp azalea ranges widely across the eastern United States, from the Gulf Coast north into New England, threading the wet margins of swamps, bogs, and stream banks where few other flowering shrubs will follow.

The species has gathered a handful of old common names over three centuries in cultivation, clammy azalea and swamp honeysuckle chief among them, and each names a real trait. Clammy and viscosum alike point at the sticky glandular hairs that coat the flower tube, catching the light and, now and then, a passing insect. Swamp honeysuckle catches the other half of the plant's character, the powerful honeysuckle-and-clove perfume that arrives in the heat of summer and carries a surprising distance on humid air. Rhododendron viscosum entered the botanical record early in the eighteenth century, and gardeners have prized the late fragrance ever since.

The pink flowers open in late spring and early summer, after the spring azaleas have finished, in loose clusters of narrow, sticky-haired trumpets above the deciduous foliage. Bees, butterflies, and hovering sphinx moths work the late bloom, drawn across the garden by scent. As with all azaleas, every part of the plant carries grayanotoxins and is poisonous if eaten, so 'Roseum' is a shrub to grow for fragrance and color rather than for any use, and one to keep clear of grazing livestock.

Few shrubs turn a wet, acidic problem into an asset so gracefully. Plant 'Roseum' at a pond or stream edge, in a rain garden, in a boggy low spot, or along a moist woodland border, where the roots find the steady moisture the plant wants and the pink summer bloom lifts a green, shaded corner. Full sun is tolerated where the soil stays reliably moist, though morning sun with afternoon shade suits warmer gardens best. Pair with clethra, itea, sweetbay magnolia, and native ferns, and site the shrub where the summer perfume can be caught near a path or a seat. For the native-plant gardener, the unusual pink color and the Woodlanders provenance make this a quietly special form to grow.