Species In Our
R. dauricum is in the subgenus Rhododendron, Section Rhodorastrum, Subsection Rhodorastra. It is distributed over a wide area, from the Altai Mountains in Russia east to Siberia, North Mongolia, Manchuria, northeast China, Korea, Japan, and Sakhalin Island. Leach says that the subalpine areas in northern Siberia between the Lena and Yeusei rivers are purple in the spring with the flowers of this species. R. dauricum was first described by Linnaeus in 1753. It was introduced into England in 1780 from the Botanic Garden in St. Petersburg. R. dauricum Sempervirens Group was introduced by Sims in 1817; this horticulturally distinct group differs from the straight species in having evergreen or mostly evergreen leaves and a later flowering time. A white form of the species was first described by De Candolle in 1839 and was introduced from Japan.
R. dauricum grows as a shrub, 5-8 feet high with a loose, upright form. It is a lepidote rhododendron with puberulous leaves (covered with minute hairs), at least some of which overwinter (as opposed to R. mucronulatum, which is completely deciduous). The leaves are shiny and dark green on the top, paler beneath and leathery. They have a rounded or broadly obtuse apex and are densely or moderately scaly and up to 1 1/2 inches (1 -3.4 cm) long. The inflorescence is terminal (at the tips of the branches) or both terminal and axillary in the uppermost leaves. The flower corolla is about 3/4-inch long openly funnel-shaped, pink to magenta, rarely white, with 10 stamens and a scaly ovary.
Perhaps the most important features of R. dauricum are its hardiness down to -25° and its very early bloom time. Depending on which country it is growing in, it can bloom from January -February to April -May. These characteristics of hardiness and early bloom have influenced many hybridizers to use R. dauricum as a parent when making crosses. One of the first, Isaac Davis, crossed R. dauricum with R. ciliatum to produce 'Praecox', a hybrid with crimson buds and pink- mauve flowers and an earlier bloomer than both parents. This cross was made in 1860 and in 1926 it was awarded The Award of Garden Merit in England. Other hybridizers have used R. dauricum: 1981 Fetterhoff's 'Dutchman Joe' [R. dauricum X minus var. minus (what used to be called the 'white Carolinianum Group')], 1972 Baldsiefen's 'Bellvale' (R. dauricum, white form, X minus var. minus (Carolinianum Group), 1978 Leach's 'Yukon' [R. dauricum X /I> minus var. minus (white Carolinianum Group)], and from the same cross, 1979 Leach's 'Hudson Bay', 1987 Lewis' 'Alfreda Wiaczek' (R. minus var. minus (Carolinianum Group dark pink form) X dauricum), and 1987 Murcott's 'Beatrice Hyde' [R. minus var. minus (white Carolinianum Group) X R. dauricum (white form].
Perhaps the best known hybrid is 'P.J.M.', a cross using [R. minus var. minus (Carolinianum Group) X dauricum (old var. sempervirens)], made in 1939 by Ed Mezitt, introduced in 1959 at Weston Nurseries, and then as a Grex in 1987. Other Mezitt crosses using R. dauricum include 'PJM Elite', 'Regal', 'Black Satin', 'Victor' and 'Minaura'. All of these dauricum hybrids are very hardy and early blooming, but vary in leaf color and winter leaf retention.
Today with so much emphasis on extending the season of bloom, both early and late, for rhododendrons, R. dauricum is certainly one to use for early bloom when choosing parents for crosses.
I have a white R. dauricum form called 'Madison Snow' I bought years ago at Lexington Gardens. It blooms very early and consistently; its flowers seem to resist spring frosts better than some seedlings. Greer also lists two more choice selections, 'Midwinter' with bright rose-purple flowers, and 'Arctic Pearl' with opalescent white flowers.
As with most lepidotes, R. dauricum performs better when planted where it gets good sun. The form is more compact and the bud set much better than when the plant is in the shade. Aside from its need for sun, R. dauricum is a tough, undemanding, excellent rhododendron, attractive all year and spectacular in early April when we need something bright bursting into full bloom.
Elizabeth Carlhian, Concord, MA