QBARS - v26n2 More on Taiwan Rhododendron

More on Taiwan Rhododendron
John Patrick, Richmond, California

New Species: This is a new introduction to cultivation to be known temporarily as RV #72001. Collected as seed 14 November, 1971, Nan-hu-ta-shan (Nankotaisan Jap.) Ca., 3200 M., Taiwan University #3179.

On 14 November 1971, Dr. Chien Chang Hsu and Mr. Chiang-Sen Kuoh left their base camp at Chi-li-ting; Ca., 2000 M. and made an unequipped assault on Nan-hu-ta-shan between breaks in the weather. It is interesting to note here that they met three different sport climbing groups returning from failed attempts at the same climb! The result of this successful and dangerous climb is seed lot RV #72001.

As far as is known, RV #72001 is not in general cultivation. This population was discovered by Dr. Hsu in August 1969. Two small seedlings brought back to Japan by Dr. Yamazaki of Tokyo University from this expedition seem to be the extent of distribution. Cuttings sent to the author by Dr. Hsu did not survive owing to rapid deterioration in the hot summer weather at lower elevation in Taiwan while awaiting transportation to the U.S.

Rhododendron RV #72001 will be described by Dr. Hsu in late 1972 after fresh, flowering herbarium material can be collected and evaluated. Fresh, fruited herbarium material was collected 14 November, 1971. A brief description here follows; not to be considered to constitute publication:

Rhododendron RV #72001 is quite heavily indumented. The rich brown, persistent indumentum extending down the entire leaf pedicel and continuing the entire length of the new growth. Internode length is 1.5-2 cm. The seed capsule measures 6x15 mm, is indumented and terminally dehiscent. Except for the somewhat wider, less revolute leaf with a cordate base, RV #72001 bears a strong resemblance to R. metternichii var. yakushimanum . From one raceme of fruit, there were eleven seed capsules, indicating that RV#72001 will have more than eleven flowers to the truss. No description of the flower color is available at this time. RV#72001 is an Alpine plant and should be accorded the same hardiness rating as R. pseudochrysanthum , the other elepidote Alpine Rhododendron found in Taiwan. It properly belongs in the Ponticum Series, S.S. Caucasicum.

With its dwarf stature, globose habit of growth, rich indumentum and very striking leaf set, RV#72001 certainly rivals the exquisite "Yaku" and is surely destined to become as equally and deservedly popular.

At this point, it seems important to mention R. nankotaisanense ; whose only difference from R. morii is a glabrous ovary; Hayata., Icon, Pl. Formos. (2) Wilson(') states that R. nankotaisanense is; "A critical species closely related to R. morii and may be a glabrous condition of that species, etc." He also states; "I did not see R. nankotaisanense in Formosa"; and that his material was a co-type specimen ^l . There does not seem to be enough difference between the two to justify species status for R. nankotaisanense . R. nankotaisanense should properly be described as R. morii var. Nankotaisanense.

Through the kind offices of the Botanical Library and Herbarium of Tokyo University, the author was permitted, on 17 December 1971, to inspect Hayata's publication (2) and to Xerox page 66 which contains the original description of " R. nankotaisanense " and gives as No. 57, the type specimen collected by S. Sasaki in April 1917. The original type specimens was inspected to be sure that it was R. morii and not RV# 72001. RV# 72001 is positively identifiable as uniquely distinct from R. morii var. nankotaisanense .

Quite possibly the reason for RV72001 not having been discovered before now was that no plant explorer had gone above timberline on Nan-huta-shan to the high, Alpine grassy areas above 3000 M. RV#72001 grows unprotected by trees in the open grassy areas and is not visible from lower elevations.

R. formosanum : A close examination and comparison of herbarium specimens at Taiwan University of several forms each of R. formosanum and R. metternichii reveals a startling similarity between these two species. Enough similarity in fact to risk questioning the placing of R. formosanum in the Arboreum Series. While R. formosanum has some resemblance to some of the Arboreum Series Rhododendron, it bears a much closer resemblance to the lightly indumented members of the R. metternichii complex.

In another article, the author has mentioned the northward migration possibilities to Japan of some of the elepidote Rhododendron from the relic populations of Taiwan. (3)

The presence in Japan of the two varieties of R. metternichii Yakushimanum and Makinoi had seemed at first to defy this theory until Rhododendron RV#72001 was collected. Within the spectrum of the indumented members of the Ponticum Series, S. S. Caucasicum found in Taiwan and Japan, it is quite easy to recognize the close resemblance when all these related types are known and the possibility of ecologic and migrant variation is allowed for.

The probability of R. makinoi being an ecotypical variety of R. metternichii as is var. yakushimanum is lent credibility when considered in the foregoing context. Nitzelius put forward this theory in "Notes on Some Japanese Species of the Genus Rhododendron, (4) upon his examination of R. makinoi.

R. mariesii: As far as is known at this time, the only deciduous Rhododendron in Taiwan is R. mariesii . Quite possibly, the deciduous species in Japan are the result of an eastward migration from the Asian Mainland which would account for the Lapponicum Series R. parvifolium and the North Asian R. aureum and camtschaticum . From the Continental Drift Theory of the separation of Continents and land masses, it can be shown that at one time, Taiwan and Japan were much closer together and attached to the Asian land mass. From the still remaining deep ocean trenches to the north and east of the Japanese Islands, evidence is available to show that they moved quite far north, partially filling that part of the weakened Earth's crust. Taiwan on the other hand, did not seem to have this weakened structure to move into and stayed relatively close to the mainland. The absence of other deciduous rhododendron in Taiwan and the scarcity of the one extant; R. mariesii , would indicate that Northern Taiwan was once the southern limit of the deciduous species.

Taiwan Rhododendron Distribution:

An important consideration to a better understanding of the distribution of Rhododendron in Taiwan is the delineation of four separate climatic zones, namely; Alpine, Temperate, Subtropical and Tropical. The following chart indicates climatic distribution of Taiwan Rhododendron, excluding the Azalea Series which will be offered at a later date.

From the foregoing, one notes zonal overlapping of some species as is to be expected within a dynamic genus such as Rhododendron. In one case, R. ellipticum , there is overlapping in three zones. As is usual, there exist ecotypes and morphological variations. These are more prevalent within the widely distributed endemic species. These ecotypes and varieties, for the most part have not been described nor given varietal designations. For instance a publicized "new" Azalea from Taiwan, seems to fit within reasonable variant limits for the species R. rubropilosum , probably the most variable of the Azalea in Taiwan and occurring in many shapes, colors and sizes and at many different altitudes and localities. These descriptions will be done by Dr. Hsu and his staff through Rhododendron Venture assistance prior to publication of his forthcoming monograph on Taiwan Rhododendron. This monograph will be included in its entirety within Dr. Hsu's monumental undertaking of the entire flora of Taiwan in ten volumes, of which the first volume is just off the press.

1. Wilson, E. H., The Rhododendron Society Notes; Vol. 11, No. V, 238.1924
2. Hayata, B., Icones Plantarum Formosanum; Vol. IX, 66. 1920
3. Patrick, J. J. R. and Hsu, C.C., The Rhododendron and Camellia Yearbook 20-27, 1971
4. Nitzelius, T., Notes on Some Japanese Species of the Genus Rhododendron. Acta. Horti. Goteburgensis, 24:135-174. 1961