Kindly sponsored by
Peter Norris, enabling the use of The Rhododendron Handbook 1998
Article from Bean's Trees and Shrubs Hardy in the British Isles
'Rhododendron reticulatum' from the website Trees and Shrubs Online (treesandshrubsonline.
Shrub or small tree, 1–8 m; young shoots soon glabrous. Leaves in whorls of up to three, at the ends of the branches, 3–6 × 1.5–4 cm, rhombic-ovate, apex acute, lower surface with short brown hairs, mainly on the midrib and veins; petioles covered with bristle-like hairs. Pedicels covered with adpressed brown hairs. Flowers 1–2(–3) per inflorescence, appearing before the leaves; calyx minute; corolla rose-purple (rarely white), funnel-campanulate, 25–30 mm; stamens 10; ovary villose, style glabrous. Flowering April-May. Royal Horticultural Society (1997).
Distribution Japan S Honshu, Shikoku, Kyushu
Habitat 400–700 m
RHS Hardiness Rating H5
Awards FCC 1982 (Hydon Nurseries, Godalming) to a clone 'Sea King', raised from seed from Japan; corolla solitary, red-purple, with upper lobe slightly paler and sparingly spotted. AGM 1993
Conservation status Least concern (LC)
Taxonomic note R. reticulatum is allied to R. nudipes but differs in the pilose petioles and leaf midrib. Royal Horticultural Society (1997)
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.
† cv. ‘Sea King’. – An excellent selection with rosy lilac flowers, which was awarded a First Class Certificate in 1982. It was raised at the Hydon Nursery from seeds collected in Japan by Dr Rokuju.
R. reticulatum f. pentandrum Wils