QBARS - v22n3 Rhododendrons and Azaleas of Japan

Rhododendrons and Azaleas of Japan
K. Wada, Yokohama, Japan

First of all I must thank you for the wonderful kindness which you showed me, by which I could come to Portland and Eugene and enjoy the beauty of Rhododendron flowers. I am a real bad speaker of English and am afraid you may not follow me in most cases. But do not mind to repeat your questions whenever necessary.

All of you know Japan as an evergreen Azalea country. Actually we have evergreen Azalea species all over Japan from near sea coast to up to several thousand feet high and from the extreme north to the extreme south, representing more than 10 different species according to environments. But not much has been said about deciduous Azaleas we have. They are represented by many different species and are giving more spectacular sight to our nature.

Visitors to Japan will recognize many beautiful purple spots against banks before Cherry blossom season and at the same time. These are a most widely spread deciduous Azalea species, called Rhododendron reticulatum . This species distributes from near sea coast up to several thousand feet high, from the north of Japan to the extreme south of Japan, including Yakushima Island. There are many different geographical forms of this species, probably over 10 different forms, to which botanists gave a different name. R. wadanum , dilatatum and rhombicum occupy central Japan and most of these are horticulturally very similar to each other. We do not feel necessary to remember so many different names.

They all have purple flowers, deeper or paler according to clone. (Slides 1 and 2) The one from Yakushima is very much different but I have no color slide now. There is also a beautiful white sport (?) (Slide 3). Rhododendron nupides belongs to this group but the flowers have a more attractive color, very similar to R. albrechtii . At this time of year, very early spring, R. albrechtii gives a colorful sight in the northern part of Japan. R. quinquefolium in the middle part of Japan. intermingles with R. pentaphyllum . Specimens nearly 20 feet high, and as broad, of R. quinquefolium , covered with snow white flowers are just a sight to behold. R. pentaphyllum also makes a sight never forgotten with a most delicate color of pink. These are first early deciduous Azaleas that give a most beautiful sight to our mountains before any evergreen Azaleas come into bloom.

In the end of April to the beginning of May, R. weyrichii comes into bloom with orange red flowers (Slide 6 and 7). R. schlippenbachii from Korea adorns our gardens. (Slide 8) This specimen is about 20 feet broad.

Toward the end of May R. sanction blooms with large purplish red flowers (Slide 9). And then R. amagianum with large orange red flowers.

R. tashiroi is an evergreen species with thick leathery leaves and belongs to the mono subseries of Tasbiroi and is a most heat and drought tolerant species, coming from near the seacoast of the most southerly part of Japan. I tried to breed from this species heat and drought resistant hybrids, using shikokianum , nupides and wadanum . R. shikokianum is a cousin of the R. weyrichii just mentioned above with orange red flowers. R. tashiroi is evergreen but the other parents are deciduous. But I got vigorous growing hybrids, highly heat and drought tolerant. These are tall growers and will be an addition to our gardens (Slides 12 to 17).

People over here honor me for my introduction of R. yakushimanum but I am personally more satisfied myself with my introduction of R. metternichii Aff. We cannot grow satisfactorily R. yakushimanum at our lowland area of the Tokyo-Yokohama latitudes because our summer night temperature is too high, perhaps like in your Texas. Still R. metternichii Aff . can grow fairly well under such heat with the added merits of blooming before any evergreen Azaleas and new shoots coming out 5 or 6 weeks after blooming (Slides 18 to 22). I first used R. metternianum for my breeding but after my discovery of this outstanding species I changed. Slides from now on are either metternianum or metternichii Aff. hybrids. Five lobed ones metternianum hybrids and seven lobed ones metternichii Aff. hybrids. The latter bloom before any evergreen Azaleas come into bloom and could invite spring one month ahead to my garden. And these hybrids have no side new shoots which often spoil beauty of flowers.

Because of our summer problem I could not use many species and hybrids which are popular over here and my hybrids are rather simple. Therefore, 1 want to quickly pass through my slides (Slides 1 to 35).

R. williamsianum cannot stand our hot summer at all. But I could obtain a few interesting hybrids (Slides 3 to 38).

Among our native Rhododendrons there are some which I have not used for breeding. R. keiskei from Yakushima Island shows deeper yellow color than the other forms (Slide 39). At the summit of Kuromi Peak of Yakushima Island, which is about 6,800 feet high, a moss-like keiskei was found. It is said to be going to be extinct there. We cannot grow this very interesting Rhododendron with us again because of the same summer problem but some plants have already been introduced by me to England and U.S.A. This is my most recent introduction. Whether it is a prostrate form of keiskei or a different species, some English people will tell us in a year or two.

Next slide (No. 40) shows R. dauricum album , R. mucronulatum (next slide No. 41) is native to Japan and is curiously the only Rhododendron which seems to grow better in Japan than in any other countries. R. chrysanthum Wada's form is the dwarfest growing form with darkest yellow flowers. I expect many hybrids from this species will come out in future. (Slide No. 42).

I think you are now tired with similar looking Rhododendron pictures. So 1 will show you pictures of some other plants. Magnolia conspicua picture is becoming well known among garden lovers because of its wonderful merits (Slide No. 43). Quercus dentateraurea is a little known tree but one of the most beautiful for its spring and fall foliage (Slide No. 44).

Next slide (No. 45) is Pieris japonica rosea daisen form, and not flamingo. Next slides (No. 46 and 47) Pieris japonica 'Christmas Cheer.' It blooms so early in the spring it is often-covered with snow but without any harm to flowers. Pieris yakusimense grandiflora 'Purity' is from Yakushima Island and has trusses hanging over with pure white large flowers. It has otherwise upright trusses.

The last is a slide of the seedling in Exbury Gardens considered best a few years ago in the garden. My rhododendrons are poor but this Exbury one is splendid with an upright truss.

Thank you.