ORNAMENTAL PLANTS OF HORTICULTURE VALUE

Hardy trees and shrubs for special environmental conditions

Rhododendron adamsii Rheder - Rhododendron

Siberia, Far East (northern part of Kxabarovsk district). In mountains at the timber line, in subalpine and alpine zones.

Evergreen small shrub with divaricate branches. Leaves oblong-elliptic, 1-2 cm long, 0,5-1,0 cm wide, glabrous, matt green above and rusty-brown beneath. Flowers 7-15 sessile in compact trusses, pink, 1,5 cm in diameter. Flowers in June-August. Very cold resistant. Z 3. New.

Rhododendron caucasicum Pall. - Rhododendron

Caucasus (the Great Caucasus and Transcaucasus), northern Turkey (Lazistan). On northern rocky slopes at 1,600-3,000 m, usually on lime free soil.

Evergreen spreading shrub about 1,0 m. Branches thick with dark brown bark. Leaves oblong or elliptic, matt dark green, with a thin fawn tomentum beneath, 4-12 cm long, 2-4 cm wide. Flowers 7-10 in compact trusses, widely funnel or bell-shaped, white with light green (later red) dotes within. In nature flowers May-July. Cold resistant, but not very much dry resistant. The true type species with white flowers is rare in cultivation. Z 5 (4).

The close related species is R. smirnowii Trutv., that occurs in southwestern Caucasis. Shrub taller than R. caucasicum, being 1,5 m high, flowers bright pink.

Rhododendron ledebourii Pojark. - Rhododendron

Siberia (Altay, southern Sayans) and Mongolia. On rocky slopes, in clearings, along streams in forests and the subalpine zone.

Shrub 0.5-2.0 m. Branches numerous. Leaves leathery, 0.8-2.8 cm x 0.5-1.3 cm. Petiole less than blade. Flowers numerous, solitary or 2-3 in axils of previous year’s leaves. Corolla pink-violet, 3.0-4.5 cm diam. Pollen violet. Closely related to R. dauricum L., differing in its evergreen leaves and bright pink-lilac flowers. Sometimes mentioned in the horticultural literature as R. dauricum var. sempervirens. Very attractive when flowering and in winter with evergreen leaves. Cold resistant. Z 4 (3). New.