QBARS - v30n1 Rhododendron kaempferi and Its Rich Variety

Rhododendron Kaempferi and its Rich Variety
Hideo Suzuki, Kumagaya, Japan
From a paper given at the 1975 Annual Meeting in Bellevue, Washington

Rhododendron kaempferi , an endemic azalea in my country, grows in the wild at low elevations throughout the Japanese archipelago which stretches 1000 miles from north to south along the Pacific Ocean. This deciduous azalea, the most abundant in Japan, is extremely hardy, being both cold and heat tolerant. Especially its form latesepalum is extremely cold tolerant.
In its type form, the flower of R. kaempferi is of five lobes, five stamens, long and wide funnel-shaped and usually pale salmon red. It is, however, very rich in color diversity and in flower shape, although it is no easy task to discover new forms.
I mentioned that the flower of R. kaempferi is rich in variety both in color and shape. As a matter of fact, its color ranges widely from pure white, creamy white with red stripes, pink, deep pink, red, salmon red, orange red, red with deep red stripes, pale purplish red, deep purplish red, and even gray. In addition to these, there are "two season flowering" and cascade forms. And in regard to the flower shape, it varies from standard single to hose-in-hose, double, polypetala, stamens incompletely petaloid, staminoid, tubular, miniature rose type, etc.
Some highly interesting forms among the many variations are:

R. kaempferi f. tubiflorum
R. kaempferi f. tubiflorum 'Longevity Treasure'
Photo by Hideo Suzuki

This is my favorite one. The flower is openly tubular and smaller than the type form. So far four different individual plants have been found, two near Tokyo, one near Kobe and the other on Shikoku Island. See map of Japan by Hideo Suzuki showing rhododendron in Vol29, No 4, July 1975. Issue of the ARS Quarterly.  Shikoku hobbyists labeled it R. kaempferi f. angustisectum when I visited there last spring. Apparently it was mislabeled, being exactly the same as R. kaempferi f. tubiflorum .
In this form the corolla is white in its throat and gets pink or red toward the margins. The most fascinating characteristic of the flower is that it stays as it is for almost two months. Then, it begins to turn its color into light green, and when fall comes it becomes crimson. Thus, you can enjoy the flower for over half a year.
My friend, who discovered one of this form, named it "Eijyuho", which literally means "longevity treasure", because the flower life is so long.

R. kaempferi, yellow form
R. kaempferi , yellow form
Photo by Hideo Suzuki

Hobbyists call it ''yellow form". To me it looks creamy in color as it is almost white. Several pure white forms have so far been found. However, this yellow form, even if it is pale, is a new discovery and is certainly one of the rarest.

R. kaempferi f. angustisectum 'Bon Fire'
R. kaempferi f. augustisectum 'Bon Fire'
Photo by Hideo Suzuki

This has been cultivated for hundreds of years. Although it disappeared for many recent decades, we have rediscovered it. It is not known whether our ancestors found it in the wild or in their garden as a mutant.
The stamens look like fine linear petals with some becoming petalized a little. When it is in full bloom, it looks as if a bon fire were burning in full swing. Hence, it is named 'Bon Fire'.

R. kaempferi f. kinshibe
R. kaempferi f. kinshibe
Photo by Hideo Suzuki

'Kinshibe' literally means "golden stamens". In our horticultural terminology, "kin" or "golden" usually means red. The flower has no petals but does have deep red stamens. The creamy anthers and pollen play a role of accent. This is also an old discovery, probably having been cultivated for over a hundred years, although it had disappeared more recently for many years. There are two forms, one from the type form and the other from f. latesepalum , an inhabitant on Hokkaido, our northernmost island. The latter's stamens are larger and more showy than the former.

R. kaempferi</i> f. <i>tachisen-e
R. kaempferi f. tachisen-e
Photo by Hideo Suzuki

The salmon red flower is by far smaller than the type form and has multiple petals. When in bloom, the plant is just like a miniature rose and is of magnificent beauty. This is another classic form cultured for a few hundred years. Two slightly different forms have also been known.