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'Rhododendron columbianum' from the website Trees and Shrubs Online (treesandshrubsonline.
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Taxonomic note Formerly in the genus Ledum, now considered to form part of Rhododendron, discussed by Bean under Ledum glandulosum. For other species formerly treated as Ledum see Rhododendron groenlandicum (Bean’s Ledum groenlandicum) and Rhododendron tomentosum (Bean’s Ledum palustre).
(Entry amended to relect the transfer of Ledum to Rhododendron, June 2022, Bean text unchanged except for name changes. JMG)
An evergreen bush, said to become as much as 6 ft high in its native home. Leaves oval or ovate, 1⁄2 to 2 in. long, 1⁄4 to 3⁄4 in. wide, dark green above, whitish and smooth beneath except for a covering of minute glistening scales, stalk 1⁄6 to 1⁄4 in. long. Flowers white, 1⁄2 in. across, produced during May in a terminal cluster about 2 in. across. Petals cupped, obovate, spreading; sepals minute, rounded, hairy on the margin; stalks 1⁄2 to 1 in. long, and, like the calyx and ovary, covered with tiny, scale-like glands. Capsules globose. Bot. Mag., t. 7610.
Native of western N. America; originally discovered by Douglas in 1826. A batch of plants was raised at Kew in 1894 from native seed, which grew and flowered very well a few years later. For some indiscernible reason the plants died one by one until none was left. It was, however, later reintroduced and sucessfully cultivated by Messrs Marchant of Wimborne, Dorset.
It is easily distinguished from R. groenlandicum and R. tomentosum by its smooth stems and leaves.
L. columbianum Piper L. glandulosum subsp. columbianum (Piper) C. L. Hitchcock – Leaves up to 3 in. long and relatively narrower than in L. glandulosum, with revolute margins. Inflorescence dense and rounded. Capsules oblong-ovoid. British Columbia to Santa Cruz County, California.