Species Portrait: Rhododendron falconeri Hooker f., 1849
Steve Hootman
Seattle, Washington
First published in the Rhododendron Species Foundation newsletter and since revised for publication in this issue of the Journal.

For sheer majesty in the genus Rhododendron , one would be hard pressed to surpass the big-leafed Himalayan tree - Rhododendron falconeri . The huge bold leathery leaves up to 14 inches (35 cm) in length are more than matched by the large, rounded inflorescence of white to pale yellow flowers. The stout growth habit and overall massive scale of this species have led some to christen it "one of the dinosaurs of the genus." The species, as now understood, comprises two subspecies, ssp. falconeri and ssp. eximium (Nuttall) D.F. Chamb. ( R. eximium Nuttall).

Rhododendron falconeri ssp. falconeri was first brought to the attention of western botanists and gardeners by Joseph Dalton Hooker who described and collected seed of this species during his famous 1948-50 Expedition to Sikkim. Although this is generally the accepted first date of introduction into the west, H. H. Davidian notes that a few plants were in gardens in the United Kingdom from seed collected by Colonel Sykes in 1830. I am uncertain if any of these plants still remain alive. There are specimens of this species grown from Hooker's original introduction of seed still growing in several old collections in the United Kingdom, including one famous plant in the gardens of Glenarn, Scotland. This species was named in honor of Mr. H. Falconer - the Superintendent of the Saharanpur Gardens in India in the mid-1800s.

Rhododendron falconeri ssp. eximium was first collected and distributed to western gardens by Thomas Booth who found it in the mountains of Bhutan/Arunachal Pradesh some time around 1850. Like subspecies falconeri , several gardens in the United Kingdom still grow ancient and massive specimens of this taxon which probably originated from this first introduction. The epithet eximium translates to "excellent," probably in reference to the ornamental foliage.

This species is a member of Subsection Falconera and is, in fact, the type species for that group. This subsection comprises one half of the "big-leaf" species, the others belonging to Subsection Grandia. Within Subsection Falconera, this species is rated as one of the finest for the garden as it is relatively hardy and extremely attractive.

Both subspecies have been reintroduced on numerous occasions from throughout their respective ranges. Subspecies falconeri is known to occur in the eastern Himalaya from E. Nepal through Sikkim and Bhutan, including adjacent areas of N.E. India (Arunachal Pradesh & West Bengal). It occurs from 9,000 to 12,500 feet (2700 to 3750 m) in coniferous forests and mixed deciduous/coniferous forest. In some areas, this species is the dominant canopy tree, forming small forests typically up to 40 or 50 feet (12 or 15 m) in height. During my expedition to Sikkim in the spring of 1997, I was able to observe this firsthand. While exploring the mountains near Bersay, we made a short trek to a traveler's hut on an isolated peak surrounded by forests of R. falconeri . In a sheltered valley nearby, we came upon one of the most spectacular displays of the genus Rhododendron that I have ever had the privilege to witness. I gazed in awe at a small grove of trees fully 80 feet (24 m) in height. The massive straight trunks were clear of branches for two-thirds of their length with the overlapping canopies high overhead preventing all but the smallest rays of sunlight from reaching the quiet forest floor.

This subspecies frequently hybridizes with another member of Subsection Falconera ( hodgsonii ) and a member of Subsection Grandia ( kesangiae ). This typically happens where the ranges of the species overlap. The former cross is quite common in the wild as the two species share a similar range and habitat. This natural hybrid has been named R. x decipiens Lacaita.

Subspecies eximium is found to the east of ssp. falconeri in N.E. India (Arunachal Pradesh) and E. Bhutan(?). The two subspecies seem to merge taxonomically and can intergrade considerably in morphological characteristics where the ranges overlap in the extreme eastern portion of the Bhutanese Himalaya and adjacent areas of western Arunachal Pradesh.

Subspecies falconeri typically grows as a tree or forms a massive shrub, often growing wider than high in cultivation. The growth is stout and the new shoots are covered with a pale brown indumentum. The bark on the older stems and trunks is an attractive peeling reddish brown. The thick and leathery leaves are elliptic to obovate in shape and usually around a foot in length on a well-grown specimen. They are a rugose matt green on the upper surface with prominent yellow veins. The lower surface is densely covered with a stunning brown to red-brown indumentum of cup-shaped hairs. The inflorescence is composed of around 20 flowers up to 2 inches (5 cm) long arranged in a massive rounded ball. The bell-shaped, eight-lobed flowers are white to cream, pale yellow or pinkish and have a prominent purple blotch. These are often slightly fragrant and their heavy textural substance gives them incredible longevity, often remaining attractive for up to a month before dropping. This subspecies blooms in mid to late spring and a large specimen covered in flowers is one of the grand displays in the natural world.

R. falconeri (Crarae). Photo courtesy of the Rhododendron Species Foundation

Subspecies eximium typically forms a smaller, more shrubby, though still massive-growing plant than its arboreal relative. It often grows into a wide-spreading plant with a flat-topped habit that better displays its magnificent indumented foliage and attractive reddish peeling bark on the older stems. The leaves are oval to obovate-elliptic in shape and covered on the upper surface with a thick and persistent layer of rusty-brown indumentum. The new growth and foliage appears late in the season and persists well into the autumn for a spectacular ornamental feature unmatched in the genus. The lower surface of the leaves is covered with a deeper cinnamon-brown, woolly indumentum. The fleshy flowers are similar to those of ssp. falconeri but typically in shades of rose or pink, often fading to cream-flushed rose after a few days.

R. falconeri ssp. eximium . Photo courtesy of the Rhododendron Species Foundation

In cultivation, both taxa perform best in sheltered gardens with a maritime influence such as New Zealand and the west coasts of Britain and North America. Like all of the "big-leafs," which are basically plants of the forest, these long lived species require protection from damaging winds and the hot afternoon sun. They require ample soil moisture during the growing season to properly develop their impressive foliage. Both are relatively hardy, rated to 5°F (-15°C) by Cox. These may seem like rather exacting conditions for cultivation, but remember, these guidelines are for optimal success. I have seen many well grown specimens in gardens with less than optimal conditions along the west coasts of Canada and the USA. Plants of both subspecies suffered foliage damage at the Rhododendron Species Botanical Garden (RSBG) in December of 1990 when the temperature dropped to 4°F (-16°C).

Peter Cox and R. falconeri ssp. eximium at Baravalla, Scotland. Photo courtesy of the Rhododendron Species Foundation

Subspecies falconeri has been used occasionally in hybridizing programs, usually being crossed with other big-leaf species. One of the most famous of the resulting hybrids is 'Fortune', a clone resulting from a cross made by Rothschild between R. falconeri ssp. falconeri and R. sinogrande which received a First Class Certificate when exhibited in 1938. A clone of the species itself received an Award of Merit when exhibited by the Gill Nursery in 1922.

Subspecies eximium has been rarely if ever used as a parent in hybridizing programs. It received an Award of Merit in 1973 as a foliage plant when exhibited by Royal Botanic Gardens, Wakehurst.

As I have stated in the past, as with all of the "big-leafs," the majority of the plants in cultivation as this species are grown from garden origin seed. Unfortunately, most of this seed is open pollinated and the resultant plants are most likely hybrids. Once you have seen the "real" R. falconeri , it is quite easy to distinguish these hybrids. Reputable nurseries like the RSBG and Glendoick offer beautiful and vigorous plants of the "real thing," grown from our own collections in the wild as well as from controlled pollination intra-specific crosses. I urge you to try this species, one of the finest in the genus.

Accessions in the Collection of the RSF

Subspecies eximium :

77/738 Windsor. I have not recorded flowering data on this clone.

77/785 Stonefield. Deep pink in bud, opening pale pink and fading to cream, with maroon basal blotching.

We have numerous recent accessions from collections made in 1988 by Warren Berg in Bhutan (BB#8816 & BB#8822). These were collected as eximium but seem to lie between the two subspecies based on foliage morphology. They have yet to bloom.

Subspecies falconeri:

75/124 RBGE. I have not recorded flowering data on this clone.

81/079 Clark: Gambrill. Light yellow flowers.

81/108 Tashi: Smith, Britt. This is a "good foliage and flower, high elevation form" collected e Ten Tashi in Sikkim.

I will be accessioning numerous new clones into the collection from my collections (SEH#'s 517, 519 & 524) in the Sikkim and West Bengal Himalaya.

References Consulted:
Chamberlain, D.F. 1982. "A Revision of Rhododendron. II. Subgenus Hymenanthes." Notes from the Royal Botanic Garden Edinburgh . Her Majesty's Stationary Office, Edinburgh, Scotland. Vol. 39(2): pgs. 259-260.
Cox, Peter A. & Cox, Kenneth N.E. 1997. The Encyclopedia of Rhododendron Species . Glendoick Publishing, Perth, Scotland. pp. 40-41.
Davidian, H. H. 1989. The Rhododendron Species . Vol. II. Timber Press, Portland, OR. pp. 166-169.
Hootman, S.E. 1997. Unpublished field notes. Rhododendron Species Foundation: Records - 1964 to present.

Steve Hootman, a member of the Seattle Chapter, is Co-Executive Director/Curator of the Rhododendron Species Botanical Garden in Federal Way, Washington.