A deciduous azalea 5 to 8 ft high with stiff, erect, somewhat sparse branches, covered with a loose brownish wool when young. Leaves diamond-shaped, 1 to 21⁄2 in. long, 3⁄4 to 11⁄2 in. wide; dark dull green and very hairy above when young, becoming almost or quite glabrous by autumn; paler and very finely net-veined beneath; stalk 1⁄6 to 1⁄3 in. long, brown-woolly. Flowers solitary or in pairs (rarely twice as many). Calyx small, five-toothed, very hairy like the flower-stalk, which is about 1⁄4 in. long. Corolla purple, almost or quite unspotted, 11⁄2 to 2 in. across, lobes oblong, 1⁄2 in. wide, the three upper ones erect, the two smaller ones more deeply divided and pointed downwards. Stamens ten. Ovary densely coated with long white hairs (brown when dry); style glandular in the lower half. Bot. Mag., t. 6972. (s. Azalea ss. Schlippenbachii)
Native of Japan; described in 1834 from a young plant without flowers growing in Knight’s nursery, Chelsea. The original description is so incomplete that Don’s species was put on one side as incompletely known until Wilson resurrected it in the Monograph of Azaleas (1921). Until then it had been known by Miquel’s name R. rhombicum. The Knight introduction was probably lost, but the species was reintroduced to Europe around 1865 and reached Britain soon after. It is quite a pretty species, bearing its showy flowers before the leaves unfold, but the colouring inclines to magenta-purple as a rule and clashes badly with reds and near-blues. It is perfectly hardy.
R. reticulatum is a somewhat variable species in the wild, and several of its forms have been given specific rank by Japanese botanists (see R.Y.B. 1948, pp. 114-16, and Ohwi’s Flora of Japan (1965), pp. 700-2). The description given above is of the form commonly cultivated in this country; all the garden specimens in the Kew Herbarium belong to it, including the original of the plate in the Botanical Magazine. This form, easily recognised in the flowering stage by the ten stamens, densely hairy ovary and the style glandular in the lower half, agrees well with the form given specific rank by Makino as R. wadanum. It is comparatively low-growing, seldom more than 8 ft high.
R. dilatatum Miq. R. reticulatum f. pentandrum Wils. – Leaves soon glabrous on both surfaces, hence distinguishable from the common form of R. reticulatum even when out of flower. Stamens five only. Ovary glandular, not hairy; style glabrous. Bot. Mag., t. 7681. Native of Japan; introduced by Messrs Veitch in 1883. Although it is very similar to R. reticulatum (wadanum) in general appearance, the distinctive characters given above appear to be well correlated and together make it more than just a five-stamened form of that species. It has the same garden value.