JARS v36n4 - R. eximium

R. eximium
Arthur W. Headlam, Bentleigh, Australia

It is not necessary to have a predilection for rhododendron species to be able to appreciate the beauty and character of R. eximium , S. Falconeri.

Under the new classifications appearing in The Rhododendron Handbook, 1980, Rhododendron Species in Cultivation, R. eximium has been placed under Subsect. Falconera, R. falconeri ssp. eximium .

I had a recollection that somewhere in my comprehensive collection of Year Books and publications on the subject of rhododendrons, there appeared some interesting information on R. eximium , and reference to my index which I started many years ago, and which I have kept up to date, enabled me to locate the following in The Rhododendron Society Notes, contributed by Members in 1919:

Rhododendron EXIMIUM, Nutt . [Figured as R. FALCONERI var. EXIMIUM in Bot. Mag. (1893)t. 7317].

R. EXIMIUM, discovered before 1853 by Booth "growing amidst ice and snow," at an elevation of 10-11,000 feet in forests on the rocky ridge and spurs of the Oola Mountains in Bhutan, and forming a stately tree 30 feet in height, is a plant of cultivation with which Members of the Society will have better acquaintance than I have, for we have no large plants of it at Edinburgh. It is an offshoot from the immediate phylum of R. FALCONERI, and there is the question, often discussed, should it be treated as a distinct species or as only a variety of R. FALCONERI? If we knew more of the aggregate we call R. FALCONERI we should be in better position to appraise the value of characters. The combination of prominent characters upon which I have relied in the past for diagnosis of R. EXIMIUM are these; the persistently bearded petioles, the rose or pink-tinted flowers, and the densely glandular ovary without any indumentum hairs and with the glands extending upwards for some distance over the lower part of the style. To these another derived from the cup-hairs of the under leaf indumentum has to be added. In R. EXIMIUM these are sessile long slightly funnel-shaped narrow tubes, the wall composed of much elongated narrow thickish-walled cells and not forming a uniformly bounded mouth to the tube, but split and divided irregularly into coarse much-branched fringed segments which end in single filaments, often fibril-like, that interlace to make the woolly surface. In R. Falconeri these cup hairs are much shorter, more tumbler-shaped, with a wall of less elongated cells, but fringed in a similar manner. The state of our knowledge at this time seems to me to warrant our following Nuttall in treating R. EXIMIUM as a species, and considerations of practical convenience in the garden lead to the same determination. No one seeing R. EXIMIUM and R. FALCONERI, as they are known in our gardens, would call them the same, and have we not the authority of so trenchant a critic of the ways of the Botanist in regard to plant-nomenclature as "W.W." for saying that the gardener abominates botanical varietal names and makes them specific if he can, so that R. FALCONERI var. EXIMIUM has become and will as I think justly remain to the gardener, R. EXIMIUM? It is as Mangles pointed out long ago an illustration of the divergence in form that is met with in Sikkim species as one travels eastwards. In Bhutan it represents the Sikkim R. FALCONERI as in other series, R. ARGENTEUM is represented by R. GRANDE, R. AUCKLANDII by R. GRIFFITHIANUM, and so on.

It is interesting that R. eximium , although having been figured as a variety of R. falconeri in Botanical Magazine, 1893, has been known as the specific name of R. eximium as suggested in The Rhododendron Society Notes. It was not for eighty-seven years, in The Rhododendron Handbook, 1980, that R. eximium , under the new classifications has been placed in the subsect. Falconera, R. falconeri ssp. eximium .

To many enthusiasts who have known this species, often for a lifetime, it will be difficult to think of it as a subspecies of R. falconeri , and this will apply to a number of other species throughout the Rhododendron Handbook, 1980, with corrections, up-datings, spelling revisions, etc.

The color plates of R. eximium supporting this paper were photographed at Kenron Park, the garden of Mr. and Mrs. Charles Carlsson, Ferny Creek, in the Dandenong Ranges. The leaves of this plant of R. eximium , (now R. falconeri ssp. eximium ), resemble those of R. falconeri , but are somewhat smaller in size; they are covered with a rusty tomentum, and as they mature, turn to dark green with deeply impressed nerves. Another attractive feature is the pale to dark reddish-brown peeling bark.

Even in the favorable climatic conditions of the Dandenong Ranges, the foliage is somewhat sensitive to summer sun and requires to be sited in a somewhat sheltered position. It also appreciates adequate watering during the growing season. Winters are not severe enough to cause any appreciable damage, but it is of interest that many plants were killed in Oregon during the 1972 freeze.