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Volume 57, Number 4
Fall 2003

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Yamato Shakunage, Part 2
Japanese Rhododendron Society

A Roundtable Discussion of Its Occurrence in Japan and Its Classification

        On Oct. 23, 1983, several of the members of the Japanese Rhododendron Society gathered in Osaka at the Osaka City Trade Center to discuss a rhododendron known to them by the name "Yamato Shakunage." The moderator was Mr. Michihiro Shida. Others taking part were Hiroichi Maehara, Yohichi Nomura, Kiyoteru Kinoshita, Tsuneo Kurosaki, Kiyoteru Kosuga and Akira Fujiama. Part 1 began in the summer 2003 issue and includes photos of Yamato Shakunage. In Part 2 the members discuss the flowers of this memorable rhododendron.

Discussion
Moderator: Now shall we change the subject to the flowers?
Kosuga: A cluster of flowers of the Yamato grown in pots is small compared to that of Tsukushi or Hon Shakunage (see box). It is about the same size as that of small-sized Azuma Shakunage which has thick indumentum on the back of the leaves. However, the Azuma has five petals while the Yamato has seven petals. Also the tube of the Yamato flower is deeper and longer than that of the Azuma. It is quite contrasting to the bell-shaped flowers of Oki Shakunage (R. metternichii v. brevifolium), whose flower has a shallow tube. Particularly, as far as the Yamato is concerned, it appears that the thinner the leaves, the longer the tubes of the flowers. Also, isn't it true that the number of flowers in a cluster is larger than the average?
Kinoshita: About ten flowers, I think. Among my potted Yamato plants, there are some which do not form a nice cluster because of the small number of flowers, but there are also some which form a shapely ball of flowers. I believe more than ten flowers are involved in such a cluster. Potted Yamato Shakunages are small plants, and their flowers are also small and in deep color. They certainly are lovable plants.
Kurosaki: My Yamato also has small flowers. But Hon Shakunage has large leaves as well as large flowers. It is a magnificent plant. In the mountains, however, some Yamato grow large.
Fujiyama: Besides, if you plant the Yamato in your garden, it grows larger and its flowers become larger, too.
Nomura: It is true that leaves and flowers of potted Yamato Shakunage are small. In the natural habitat, on the Ohmine Mountain Range, there are many different sizes. Ones at lower elevations are relatively large...though this might be due to the cross-fertilization with Hon Shakunage. Especially those in the southern part of the Ohmine Mountain Range are large. But some of those at higher elevations, above 1,000m, seem to have small leaves and flowers. All the Yamato flowers have seven petals even if they are small ones.
Moderator: There are individual differences among flowers of Yamato and Hon Shakunage and each flower bears seven petals with gorgeous trusses of fifteen to twenty flowers. At Daito village (elevation, 650m) near the foot of Mt. Ohmine, I saw hundreds of transplanted Yamato Shakunage, whose roots were moved from the mountain to the garden about ten years before. They had large leaves...yes, their sizes were no different from those of Hon Shakunage. But the leaves still retained the beauty of a typical Yamato. The shape of the leaves is gracefully streamlined like a young ayu (sweetfish) with a slight inward curl and the back of the leaves had thick reddish brown indumentum. Besides, their flowers were large, and they were all in all magnificent. Those Yamato had about fifteen flowers in a cluster. If only the flower clusters but not their leaves were examined, they look almost like Hon Shakunage. Only Yamato's mesophyll is thicker than that of Hon Shakunage. Consequently, Yamato's petals are also thicker than the other, which will distinguish the two clearly. Yamato's petals are almost as thick as those of the Yakushima. This is also true for the potted Yamato which has small leaves.
Maehara: Those Yamato growing wild on the high elevation of Misen and Mt. Inamuragadake have flowers of medium sizes, 3.5cm-5.8cm in diameter, though we can also find, on occasion, flowers 2cm across. It is considered to be one of the characteristics of the Yamato to have small flowers, but there are some flowers about 7cm in diameter near Zenki in the south. The number of flowers in a cluster is generally six to twelve, and therefore it is hard to form a ball-shaped truss. It tends to become a wheel-shaped truss. Of course there are some shaped like a round ball. The tip of the petal is pointed and shaped just right. The colors of flowers are dark pink or light pink, and blotches in the flowers are also in many colors - red, brown, orange, light green, and pink. I haven't yet seen the red-flowered Yamato, which has deep red flowers.
Kosuga: The color of the Yamato's flowers is on the darker side of pink. The redness at the time of opening of the buds does not last long. Compared to the Yakushima, the color fades fast, doesn't it?
Moderator: However, the color of Yamato Shakunage's flower does not fade to white, does it?
Maehara: Generally speaking, Yamato's flowers do not fade much. Near Takasaki Yokote there are Yamato Shakunage whose flowers have deep red streaks on the outside of petals. As the flowers grow old, the color of the petals fades, but not the red streaks. So you'll see the flower like the old Japanese navy flag.
Moderator: Yes, I saw those red streaks for sure. And those streaks do not fade easily. It looks the same as those red veins in the new leaves. Anyway, the leaves and flowers come from the same part of the plant to start with. The more beautiful the flower is, the more red are the streaks, and they do not fade until the petals scatter. Red flowers are seen among Hon Shakunage and Hosoba Shakunage on the Ohdaigahara. This will particularly give an impression that Yamato's flowers fade easily. At any rate, this fading of the color in the flowers as well as the thickness of them is among the important characteristics of the Yamato.
Kinoshita: I think flowers of the Yamato are not thin enough to be transparent like those of the Yakushima or Hon Shakunage.
Moderator: Are there also flowers with five to six petals or eight petals?
Maehara: I looked for five-petal Yamato Shakunage in the south such as on Mt. Shakagadake. The first one I thought I found on Mt. Shakagadake turned out to be a flower of the Aka Yashio (R. pentaphyllum) with missing petals. The fact is that in the southern part of the Ohmine Mountain Range we cannot find five-petal Yamato Shakunage. One day on the way back from Mt. Inamuragadake, I checked one of the Yamato blossoms thrown by a climber beside the path. That one had five petals, so I looked for some more nearby. There were five-petal Yamato growing wild there as well as seven-petal flowers mixed in with them. However, all five-petal blossoms are found at the Dainichisan in Mt. Inamuragadake. I have seen them over there, but they were growing on the steep rocks. You cannot collect a sample without risking your life. I saw three or four Yamato plants growing on a shelf of the rocks. Especially the one on the very north among them had all five-petal blossoms. Its petals were extended circles.
Moderator: Ordinarily Yamato blossoms have seven petals, haven't they?
Maehara: Yes, the standard one has seven petals. So one might think it should have fourteen stamens, but this is not so. Often it has odd numbered stamens. There seems to be no correlation between the numbers of petals and stamens. Whatever it is, small kinds of Yamato Shakunage such as Hime Yamato Shakunage do not produce good looking blossoms, do they? When small conical blossoms come out, it's a disappointment. (laugh)
Moderator: How about white Yamato blossoms?
Fujiyama: White blossoms in the Yamato are rare, aren't they?
Maehara: It might be that the Yamato decided not to give white blossoms, since people made such a big fuss about the white blossoms, once they came out, calling them "white phantoms." At any rate, it is hard to get a pure blood Yamato plant which gives pure white blossoms. There are many stories such as this. After begging to get a branch of a Yamato plant with pure white blossoms, it was grafted to his own tree. But what came out from this turned back to the original pink flowers. So it does not pay to pay such an outrageous price as is usually placed on Yamato plants with white flowers. If you really want a white-blossomed Yamato, you have to sow your own seeds and go through the selection process. This is the most certain way to get that. I got two such plants out of seeds planted in six large planters. They were the perfect blue blood of the white Yamato.
Moderator: Most wild white Yamato usually have some pink in them, haven't they? However, I have seen the white Yamato with my own eyes three years ago. One person in Daito village had it. I brought back about ten pictures of the blooming Yamato. It did not have any pinkness either in the leaves or stems or in new leaf buds. Of course, the flower buds were white with a tint of yellow. There were five to eight flowers in each cluster and nicely in one bunch. Each flower had seven petals and was small. Perhaps it was because the bush itself was weak. The leaf had thick indumentum on the back and was relatively small. This was the only Yamato I have seen with white blossoms, but unfortunately it was impossible to get the plant.
Kurosaki: Then the white Yamato really exists, doesn't it?
Moderator: I have obtained, after hard efforts, a smoky-white (almost white) Yamato plant, but its indumentum on the back of the leaves is thin. Since it is dark brown or red and very pretty, no doubt it is a Yamato Shakunage, but its indumentum is ridiculously thin. It almost makes me think it is a cross with Hon Shakunage. Its leaves are small and shiny. I found out about this from the news that NHK (Nihon Hoso Kyokai, Japan Broadcasting Corporation) had a documentary on it and obtained one, but I lost it from the recent severe heat wave. It was collected in the wild from near the top of Mt. Shichimensan and was a magnificent plant about 1m across. I have made several grafts out of this.
Kurosaki: Did it have white flowers?
Moderator: Actually I got this because it is supposed to have pure white flowers, but it was such a disappointment to see red veins in the new leaves in spring. (Everyone has a big laugh.) Then I gave up expecting to see pure white flowers on this plant, but it was a beautiful plant with milky leaves and red veins at the time of new leaves. The whiteness of the leaves comes from the milky indumentum on both sides of the leaves. However, another spring later, I was very excited about the prospect of having a pure white flower. One night after work I was walking through my yard. Then I saw a flower bud starting to open like white mist. The bud was pure white with a faint pink even in the dark! Three days later it opened. The petals were pure white with red blotches. The flower stalk was bright red. It has smoky-white (almost white) blossoms last year and the year before, but in the summer of Showa 58th year (1983) it had pure white buds and pure white flowers. I don't know why, but it may be due to the climate variation. Even its blotches were greenish dark brown, and it was almost all white except for the pink flower stalk. I named it "Seven Face White" or "Hichimen Shiro."
Kurosaki: If the flower bud was cut open, it must have had some pink, mustn't it?
Moderator: Yes, I think so. There were forty to fifty buds on it, and the ones on the top of the plant, where the sun was strong, had some pink in them. From those buds underneath on the side branches, in the shade, smoky-white (almost white) flowers blossomed. Their flower stalks were also without pink in them.
Kurosaki: The smoky-white ones sometimes turn white and in another time to faint pink.
Maehara: The picture of "white-flower" Yamato which is displayed at the Bonsai Center at Daito village is actually yellowish, isn't it?
Moderator: If you look at it carefully, it is smoky-white, almost white but not pure white.
Kosuga: The other day I went to Mr. Oomae's house. As you recall, they had a garden in the back, but they were building a house on it. So I am afraid that Yamato with smoky white flowers, which he prized so much, must have gone. Mr. Shida (the moderator), please take good care of your Yamato.
Maehara: I have seen a white-flowering Yamato Shakunage on the Misen, but too many people must have been picking the branches. That particular plant was all bare. The next time I went up, it wasn't there any more.
Kurosake: Was that a privately owned mountain?
Maehara: It seems to be private property, belonging to a paper company called Jyujo Seishi Co. or some such.
Unnamed participant: That is why it is necessary to transplant even smoky-white (but not pure white) Yamato Shakunages to our garden and to cultivate them for selection.
Maehara: Yes, but that plant won't mature. It may be that if we use a new technique of cross-fertilization, the result may be good. At this stage, the usual cross-fertilization technique will not mature to grow seeds, if it is a self- pollination.
Moderator: I believe that's generally true. My self-pollinated smoky-white Yamato won't form even a small shriveled capsule nor seeds.
Kurosaki: Then does no one have a pure strain of white Yamato Shakunage?
Moderator: No, I don't believe so, at least among those rhododendron lovers in cities. I imagine, though, there are some, in the villages near Mt. Ohmine, which are being well cared for.
Fujiyama: I imagine one can find one if he searched the Yamato's natural habitat well enough. Sooner or later from among the seedlings, a white one should appear.
Moderator: The leaves of Tsukushi Shakunage from Mt. Mimata became larger and more beautiful when the plant was brought down from the mountain, but it's the opposite for the Yamato. When the Yamato is grown as a bonsai, the leaves become smaller.
Maehara: That phenomenon is called "constringence" of a plant. Between the Mimata and Yamato it is opposite. Also the way the branches grow are opposite. The Yamato does not grow to the side very much, but the Mimata does.
Kosuga: That must be so. I haven't heard of the Yamato growing sideways yet.
Fujiyama: Though Tsukushi Shakunage, for example, tends to grow sideways when it is transplanted to fertile soil, as for the Yamato nothing like that happens.
Moderator: It means that the Yamato's adaptation to the environment is not very good.
Kinoshita: So, for pot planting as a bonsai, Azuma and Yamato Shakunages are the best kinds, since they become small.
Fujiyama: But my Yamato grew to about 1.5m tall in five to six years when I planted it directly in the ground at a good location. So, that is not true if you plant in the ground.
Moderator: As far as the thickness of the indumentum of the leaves is concerned, even self-pollinated Yamatos resemble their parent plant, don't they?
Maehara: Yes, they do. Among those with thick indumentum there are none with dark color, but the color of the indumentum tends to become lighter.
Moderator: Are those young self-pollinated plants strong?
Maehara: Those on the top of the mountains seem to be a bit weaker than those from the lower elevation. It's only my impression, though. I haven't really carefully examined them. However, if you are going to sow seeds of Yamato, you should get them from the top.
Moderator: How is Yamato Shakunage as a parent for cross-fertilization to make various kinds of indumentum, for example?
Maehara: I think Yamato's pilus is recessive in a cross. If you cross Yakushima Shakunage FCC with white-flower Yamato Shakunage, the product looks like Hon Shakunage.
Fujiyama: But the cross between Yakushima and Tsukushi has good thick indumentum close to those on Yakushima.
Maehara: When I crossed "Blue Pacific" with white-flower Yamato, no indumentum appeared in the cross. Nothing even close to Yamato came out.
Fujiyama: Since Yamato Shakunage is resistant to color fading, it is a good candidate as a parent in cross-fertilization, I think. I crossed Yamato with R. williamsianum. The young plants grew well, but I lost more than half of them in the severe heat wave of Showa 58th year (1983). At any rate they have indumentum on the back of leaves. The leaves look just like those of "Miniature Pink."
Nomura: I made a cross between Yamato Shakunage and RM11. This cross seems to be more resistant to heat than Yamato. It did not grow as big as "Sekisei" (red star) Shakunage, but grew twice as big as Yamato Shakunage. How about the indumentum. It will be another two or three years before I can tell.
Unnamed participant: How many kinds of rhododendrons do you usually plant every year?
Fujiyama: I cross-fertilize five to six kinds myself, but I sow many more kinds either given or bought from here and there.
Moderator: "Zangetsu" Shakunage, which was named and grown by Mr. Maehara, is a cross between Yamato and Kibana (R. aureum) Shakunages, isn't it? Did Mr. Kurosaki do the actual cross-fertilization?
Kurosaki: Yes, I did. I crossed Yamato with Kibana (R. aureum), but self-pollinated plants from it were more of the Yamato type though they had no indumentum. I still have three good plants left with me, but I have asked a Buddhist temple located at 780m to take care of them for me. These three have all Yamato's leaves.
Moderator: "Zangetusu" (Morning Moon) Shakunage named by Mr. Maehara looks closer to Kibana (R. aureum), doesn't it?
Maehara: Actually most of them looked like the Yamato type. The Kibana type was rare among the crossed plants, and I have kept only one plant.
Kurosaki: The picture you gave me showed a bit of yellow on the flower.
Maehara: I think the color came out too strong in the yellow. Actually it was more like a creamy color. At the start of bloom, it has a faint pink in it, but later it becomes a creamy color, and finally closer to white.
Moderator: Isn't it a good idea to cross that with Kibana again?
Maehara: Yes, that's right.
Moderator: How about crossing "Zangetsu" with Kurohime Shakunage (see box) produced by Mr. Kesato Arakawa? Then the yellowness of the flowers may gradually come out as the dominant color. Besides, if we could cross that further with white-flowered Yakushima or white-flowered Azuma (R. degronianum subsp. degronianum) or white-flowered Mimata (R. degronianum v. heptamerum), it will no longer be a dream to see yellow flowers on Mimata-like plants with indumentum on the back of the leaves, will it?
Kurosaki: Seedlings usually die easily at the time of transplanting, so five or ten of them will not be quite enough to keep us going. I am thinking of giving five seedlings, which have already grown for about two years, to someone who is good at growing rhododendrons with the condition that he will give me back some later. Right now I have a cross between Yamato and R. simiarum which is getting large. I can hardly wait to see the flowers.
Maehara: Among those I've crossed, the cross between white-flowered Yamato and white-flowered Hosoba (see box) gave Hosoba type plants also. This one has a bit thinner indumentum but is well- branched like the Hosoba. Its leaves are very long.
Moderator: Hosoba Shakunage is strongly dominant, isn't it? Next, let's discuss the flowering season of Yamato Shakunage in the wild. When is it?
Maehara: It starts around May 20 starting at the lower elevation. Then they gradually bloom upward in order. On the top of the Misen, it is around June 10, right at the rainy season. It rains a lot around that time.
Fujiyama: There is a saying, in both Yakushima and Ohdaigahara, "It rains thirty-five days a month."
Kosuga: The flowering season of Yamato seems to be from the end of May to the middle of June.
Nomura: In Amagawa village they bloom in early May, during the golden week (consecutive holidays usually from May 1 to May 5). The elevation there is about 800m.
Moderator: When is the flowering season for those Yamato growing in our gardens at low elevation?
Nomura: As you might expect, it is early April.
Kinoshita: Mine are in the early half of April.
Fujiyama: So are mine.
Kosuga: My Yamotos bloom one to two weeks after Azuma Shakunage blooms. It is during the early half of April, when Tsukushi and Hon Shakunages also start to bloom.
Maehara: But among Azuma, Hon Shakunage and Yamato, Yamato starts new leaves much earlier than the others.
Nomura: Yes, you are right.
Moderator: Are there any double or semi- double flowers of Yamato in the wild?
Maehara: No, there are none.
Moderator: Next, how about the soil conditions or fertilizers and such for growing Yamato Shakunage? Are there any particular points we have to keep in mind?
Maehara: No, there are not any, specially. But the one I planted at Akadama (with a kind of natural soil that is good, in particular, to grow rhododendrons) is not doing very well, since the soil there does not dry well.
Nomura: There are no special conditions on growing Yamato, but it is hard to root from a cutting, isn't it? I have had very little success.
Maehara: It seems to work if you use cuttings of around June 10, when the new leaves have just finished coming out, and also if the cuttings are rooted in sealed containers.
Moderator: I saw, many times, Hon Shakunage blown down by a typhoon, at its wild habitat, Mt. Suzuka, and that from the broken branches some roots were growing. Have you seen anything like this with Yamato?
Maehara: No, I haven't seen any roots coming out from the broken branches of Yamato yet, but I have hardly seen any blown down Yamato plants in the first place.
Moderator: Aren't there any Yamato so tall that it may be blown down in the wild?
Maehara: At the lower elevation of the Misen, there are some Yamato about 3-4m tall. In the middle of this mountain, they are about 2-3m, and at the top or near to the top they are about 1-1.5m. So, on the whole, there are not many tall ones, though they have a lot of branches out.
Fujiyama: Yamato Shakunage is fit for training as bonsai as well as for admiring in the yard. It has reddish indumentum on the back of the leaves, flowers with hard-to-fade color, and graceful branches as well. It is also a good candidate for a parent in cross-fertilization.
Kinoshita: Still Yamato Shakunage is a kind of mysterious plant, which blooms quietly deep in the primeval forest of the Ohmine Mountain Range, where an age ago even priest trainees and hunters did not go in and was a magical fairyland of a mountain. There are many aspects of Yamato Shakunage to be explored. This, in turn, mysteriously stirs our attraction to Yamato Shakunage. I hope to continue research on Yamato with the cooperation of the Nara Branch, Kyoto Branch and Mie Branch.
Moderator: Thank you all for coming today.

Classification of Yamato Shakunage and Other Rhododendrons of Subsection Pontica of the Omine Mountain Range and the Ohdaigahara of Japan
Japanese Name Former Classification Current Classification
Yamato Shakunage R. metternichii var. micranthum R. degronianum ssp. heptamerum var. hondoense f. micranthum
Hon Shakunage R. metternichii var. hondoense R. degronianum ssp. heptamerum var. hondoense
Yakushima Shakunage R. metternichii ssp. yakushimanum R. degronianum ssp. yakushimanum var. yakushimanum
Tsukushi Shakunage R. metternichii R. degronianum ssp. heptamerum var. heptamerum
Azuma Shakunage R. degronianum R. degronianum
Hosoba Shakunage R. makinoi R. makinoi
Kurohime Shakunage R. x kurokimense R. x kurokimense  (R. aureum x R. degronianum)
Kibana Shakunage R. aureum R. aureum

Volume 57, Number 4
Fall 2003

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