JARS v36n2 - Rhododendron ciliatum

Rhododendron ciliatum
Herbert Spady, Salem, Oregon

R. ciliatum was described by Hooker in 1849 in Rhododendrons of the Sikkim Himalaya . Along with R. maddenii and R. dalhousiae it was one of the first species of subsection Maddenia to be described and introduced into cultivation. In fact, it was among the first rhododendrons to be introduced from the Sino-Himalaya. Specimens have been collected from Nepal, Sikkim, Bhutan, and Tibet. The type was described from the Lachen and Lachung valleys of Sikkim. These species are on the fringe of the major concentration of the Maddenia. The subsection is more heavily concentrated to the east. Seed collected from higher elevations up to its maximum of 13,000 feet has proven to be the hardiest, but at the same time the least fragrant. It has a pleasing, but not highly penetrating fragrance. Plants have been in cultivation for many years, so the species' characteristics are rather well known. Blooming as soon as two years after sowing, it may well have been one of the first of Hooker's introductions to flower. In moist cool areas such as western Scotland, numerous seedlings spring up voluntarily.

Botanically, R. ciliatum is described as having relatively small but not tiny leaves. The leaves are elliptic and always fringed with stiff hairs. There are also hairs on the upper surface of the leaves, usually shorter. From these hairs comes the name, cilium , Latin for eyelid, hence eyelash. Being of the subgenus Rhododendron, it has scales on the leaves, but there are neither hairs nor scales on the corolla. There is a conspicuous five lobed calyx.

Being one of the hardiest of the Maddenia subsection R. ciliatum has survived well in Great Britain and to a lesser extent in the Oregon, Washington, and British Columbia region. It is hardy to only about 10° F. Though relatively tender, plants recover well from severe damage. Frequently when rhododendrons rated much hardier die completely from extreme cold, R. ciliatum will survive and grow out from wood around the base of the plant. Many plants survived the vicious Pacific Northwest winters of 1955 and 1972 in this manner. After such disasters, it is blooming again in a year or two as a more compact plant. Both flower buds and flowers are damaged by spring frosts. Since it blooms in March this damage is not uncommon, but the blooms may still last as long as many late blooming rhododendrons fried by a heat wave. Spring tenderness contrasts to toughness as far as early fall frosts are concerned.

The usual flower color, and perhaps the most pleasing, is white streaked with a flush of pink. It has been described as white streaked with purplish mauve, pure white, strong pink, and even yellow. The author has no experience with such unusual color forms. Generally the inflorescence contains three or four flowers, but the maximum is five. They are held and displayed rather loosely with a flat top. Overall the large flowers and loose truss give a light and airy grace which goes well with the character of the plant's growth.

Although described as a dwarf or semi-dwarf it certainly can not always be called a compact plant. There is often an openness that is generally typical of the Maddenia. Still, this species does not have flowers perched on long bare stems as many of the Maddenia do. Of course, it is more compact in full sun than in deep shade. It is a heavy and faithful bloomer and has good heat tolerance. Both in the wild and in cultivation, groups of plants tend to form thickets about three feet high in twenty years. This makes a good planting in front of taller growing rhododendrons, especially those of bright color that bloom at the same time as R. ciliatum . It appreciates plenty of moisture and good drainage, and generally tolerates a slightly higher pH than many rhododendrons.
Many of the species' good qualities extend to its tender offspring such as 'Snow Lady' and 'Cilpinense'. Its good qualities plus excellent hardiness appear in the cross with R. minus (syn. R. carolinianum ), 'Dora Amateis'.