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Species In Our Midst
Rhododendron atlanticum

by Susan Clark

Rhododendron atlanticum
Picture by S & J Perkins
Rhododendron atlanticum in Salem, NH

Rhododendron atlanticum

This deciduous azalea is found along the eastern United States from Delaware to Georgia in the Coastal Plain. It favors sandy pinelands, swamps, shrub bogs and stream-banks. It seems to be closely related to R. viscosum and arborescens, our two other white, unblotched azaleas; it is distinguished from them by its blooming before or during leafing. The plant was first collected by John Clayton in 1743 and sent to the British Museum; unfortunately that specimen was overlooked by Linnaeus in his great classification and not 'rediscovered' until 1916. R. atlanticum has greater respect in England than in its own country, as often happens. R .atlanticum is a multistemmed, upright and not heavily branched shrub, usually three to four feet high. It is very stoloniferous and in its native sandy soil has sometimes formed clumps of an acre or more! Heavy soil substantially restricts its lateral development.

Much of the plant is covered with variable amounts of hair, prompting the technical taxonomists to indulge in copious Latinate compounds to describe the young twigs, buds, petioles (leaf stems), pedicels (flower stems) etc. The leaves are usually hairless, or glabrous, but even there the description can be exhilaratingly dense, as when K.A.Kron describes R. atlanticum's upper leaf surface (A Revision of Rhododendron Section Pentanthera, in the "Edinburgh Journal of Botany"): "… adaxial surface glabrous, occasionally sparsely covered with unicellular and multicellular gland-tipped hairs, or with only multicellular gland-tipped hairs, rarely densely covered with only unicellular hairs...". At any rate, R. atlanticum has mid-green or bluish-green leaves, about 1 1/2 inches long and 1/2 inch wide, smooth-edged; the under-surface is usually paler in color.

The flowers are produced just before or during leafing, 4 to 10 flowers carried in a short raceme. They are white, occasionally yellow or often white tinged with pink or lilac, especially on the outside of the tube. They have a wonderful, sweet and heavy fragrance. They are tubular-funnel shaped up to 1 1/2 inches. The stamens and style protrude well beyond the petals, as many azaleas do. It blooms in the Boston area at the end of May.

R. atlanticum is easily propagated by division and root and stem cuttings. It passes this characteristic on to its hybrid offspring. It readily interbreeds in the wild with R. canescens and periclymenoides, the latter giving us the beautiful 'Choptank Hybrids' with their pale or purplish pink flowers.

R. atlanticum seems quite hardy in this area, with reported bud hardiness to -15°F. It is a charming, undemanding plant, attractive in an understated way all year, and glorious in bloom. It should be grown more often!

Susan Clark, Concord, MA

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