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 viscosum' from the website Trees and Shrubs Online (treesandshrubsonline.
Deciduous shrub or small tree, to 6m; young twigs usually eglandular-hairy, occasionally with gland-tipped hairs. Leaves (3–)4–6(–8) × 1.3–2.3(–3.1) cm ovate or obovate to elliptic, lower surface glabrous, sometimes glaucous, occasionally with eglandular and/or gland-tipped hairs. Flower bud scales with outer surface sparsely to densely covered with unicellular hairs or glabrous, margin unicellular-ciliate, occasionally glandular below. Flowers with a sweet fragrance, appearing after the leaves have expanded, 3–14, in a shortened raceme; calyx 1–2(–5) mm; corolla white, occasionally with a pink or purplish tinge, rarely completely pink, funnelform, tube gradually expanding into limb, outer surface usually covered with unicellular and gland-tipped hairs, 20–57 mm. Capsule covered with eglandular or gland-tipped hairs. Flowering May-July. Royal Horticultural Society (1997)
Distribution United States E & S
Habitat s.l.-1,500 m
RHS Hardiness Rating H6
Awards AM 1921 (F.G. Strover, South Norwood, London) as Azalea viscosa glauca; flowers white. AGM 1993.
Conservation status Least concern (LC)
Taxonomic note This is a variable and widespread species. Royal Horticultural Society (1997)
A deciduous shrub of bushy habit eventually 6 to 8 ft high, with twiggy branches, hairy when young. Leaves thinly arranged along the shoot or in a tuft of five or six at the end, obovate, 1 to 2 in. long, tapering to a short stalk at the base; dark green and glabrous above, paler and bristly along the midrib beneath; margins bristly. Flowers produced during June and July at the end of the previous year’s shoots, six to twelve together in a cluster. Calyx small, and like the slender flower-stalk, glandular-hairy. 3⁄4 in. long, curved, hairy. Corolla white or pink, 1 to 11⁄4 in. long, the lower half is a narrow tube often more highly coloured, the upper half five expanded oblong lobes 3⁄4 in. long. The whole corolla, but especially the tubular part, is covered with sticky hairs. Stamens exserted. Ovary clad with usually gland-tipped bristles; style longer than the stamens, downy in the lower part. (s. Azalea ss. Luteum)
Native of eastern N. America; introduced in 1734, and still one of the most delightful of garden shrubs because of its late blossoming and its exquisitely fragrant flowers. It is the reputed parent, or one of the parents of a great number of garden azaleas. Loddiges in their catalogue for 1836 gave a list of one hundred and seven varieties, which, according to Loudon, were hybrids or varieties of R. viscosum. The identity of many of these old varieties is lost, but some are still to be obtained under their old names. Relatively few, however, show any viscosum ‘blood’, but rather that of R. periclymenoides and R. calendulaceum. The viscosum group at the present time is, as a matter of fact, a rather limited one, but is well distinguished by the lateness in flowering, strong fragrance, and the viscous blossoms.
Azalea serrulata Small
Azalea viscosa var. glauca Ait