Friday, November 14, 2014

Japanese Flora in Autumn

Autumn color at Buchholz Nursery

Japan begins in the north with the island of Hokkaido, just below the Sea of Okhotsk, and ends – of the four major islands anyway – at the southern tip of the island of Kyushu. The total area is slightly smaller than the state of California, but Japan's length extends 1,869 miles or 3,008 km. A national hobby, actually an obsession, is the Japanese fascination with the blooming of the cherry trees which begin, obviously, in southern Kyushu and ends six weeks later in the north of Hokkaido. The famous autumn color, in reverse, begins north in Hokkaido and finishes in Kyushu, sometimes as late as December. I've never been to either Hokkaido or Kyushu, and my only visits have been to the largest island of Honshu. I hope to, one day, witness the advance of the cherry blossoms in spring and the descent of fall color. In the meantime let's take a look at the splendid autumn colors of the Japanese flora.

Acer micranthum

Most gardeners think of the palmatum species when it comes to colorful Japanese maples. Or else Acer japonicum or Acer shirasawanum. But there are a number of other species that are brilliant as well, such as Acer micranthum. For some reason it is rare in western gardens, when it is a small, pretty and hardy tree with great fall color as you can see. I think I am one of the few American nurserymen who champions the species. Maybe the problem is the scientific-sounding species name, which is simply referring to the smallish flowers. The seed is also small, but it turns to an alluring pink in autumn. A. micranthum is native to southern Japan, occurring on the southern parts of Honshu, Shikoku and Kyushu, and locally it is known as Kominekaede, or "small maple." Acer micranthum is a striped-bark maple, and we have successfully grafted it onto Acer davidii and tegmentosum, but it also strikes from rooted cuttings in summer under mist. In appearance it is rather like Acer tschonoskii, also from Japan, but which occupies a more northern range. I wonder why there are no cultivars of A. micranthum, no showing off of extreme variation of the type like with palmatum; and again, that is perhaps why it labors in obscurity.

Acer capillipes

Acer rufinerve

Acer capillipes is another Japanese snake-bark species, known as the "capillary maple," duh, but fortunately also referred to as the "Kyushu maple." It is native to the mountains at the same locations as Acer micranthum, and I wonder if they would ever hybridize. The bark is olive-green with white vertical striations and brown horizontal lenticels.* A. capillipes is related to the similar Acer rufinerve, but the former features red petioles – the stem that hooks the leaf to the branch – and the hairless, or thinly-haired leaves. A. rufinerve, or urihadakaede to the Japanese, has rufous hairs on the underside of the leaf, and it flowers later in the spring than A. capillipes. Both A. capillipes and A. rufinerve grow to medium-sized trees, but they are usually only found in arboreta in America – a situation that I'll never be able to fix. For example, neither Acer micranthum nor Acer capillipes can be found at the Portland Japanese Garden, a spectacular place that bills itself as "the best Japanese Garden outside of Japan."

Betula albosinensis

*A lenticel is a pore that provides a pathway for the exchange of gasses between the tree and the atmosphere through the bark. The name lenticel is derived from its lenticular, or "lens-like" shape, and is particularly apparent on the birches.

Acer crataegifolium 'Veitchii'

Acer crataegifolium features hawthorn-like leaves, and it too comes from the central and southern Japan. It is known as urikaede, which refers to the bark resembling the skin of a melon, similar to urihadakaede, or Acer rufinerve. There are a handful of variegated crataegifolium cultivars, but I don't know of any other selections, like a weeping or dwarf version. The species is nobody's favorite tree, and in my experience I find it to be rather wimpy. Everything is redeemed in fall, however, with exciting yellows, orange and reds. A. crataegifolium was introduced by Charles Maries in 1879, when he was working for the Veitch Nursery, but Phillip von Siebold had it classified as early as 1845. I think it was lame to classify a species because of its resemblance to some other plant, like with Acer crataegifolium, Carpinus betulus, Acer carpinifolium etc. Botany would be better served if poets rather than scientists were given the naming privilege.

Acer pycnanthum

I have the rare Acer pycnanthum in the Flora Wonder Arboretum, and it was propagated by grafting onto the similar Acer rubrum. The name pycnanthum is derived from pycnanthus, meaning "flowers in dense clusters," and indeed, the red-flower display in early spring is wonderful. The species is limited to a small area near Nagano on the Honshu island. When my wife was a student of landscape architecture at the prestigious Tokyo Agricultural University, the professors made a big deal about a pycnanthum specimen on the grounds, and demanded that all students remember and cherish the tree. Meanwhile, I was growing my specimen before I was eventually lucky enough to marry a Japanese woman.

Enkianthus campanulatus

Enkianthus campanulatus 'Princeton Red'
Enkianthus campanulatus 'Showy Lantern'

Enkianthus campanulatus 'Siko-kianus'
Enkianthus campanulatus 'Summer Hill'

Enkianthus perulatus

Enkianthus perulatus

There are three species of Enkianthus native to Japan, E. campanulatus, perulatus and cernus. I grow the first two but I have never even seen the cernus species. The genus was classified by the Jesuit missionary and botanist, Joao de Loureiro in 1790, and the name combines the Greek words enkyos for "pregnant" and anthos for "flowers." E. campanulatus is the most common in cultivation in America, and we have grown the cultivars 'Akatsuki', 'Albiflorus', 'Hollandia Red', 'Kisoji no haru', 'Miyamabeni', 'Princeton Red', 'Showy Lantern', 'Siko-kianus', 'Sinsetu', 'Summer Hill' and 'Variegata'. Autumn colors range from orange to red to purple, often at the same time, and the small leaves persist for at least a month in my gardens. I like growing the various cultivars, and do so for the best flower color in spring, and for the best autumn foliage color. The shrub is especially brilliant after a rain with drops on the leaves, and then the sun peeks out and makes everything sparkle. Enkianthus perulatus is wonderful as well, with dainty white flowers and rich orange-to-purple fall color.

Quercus dentata 'C. F. Miller'

Quercus dentata 'Pinnatifida'

Quercus dentata 'Pinnatifida'

Quercus dentata is the Japanese "Daimyo oak," and we grow the cultivar 'C.F. Miller', even though it was first selected in Korea by Carl Ferris Miller at the Chollipo Arboretum. Oddly, Hillier in The Hillier Manual of Trees and Shrubs claims that it has "no autumn color," but in Oregon it certainly does. At first the foliage changes to orange and then to brown. Leaves stay on the tree throughout most of winter, and their brown color is not dead-looking at all – it is a warm mocha color. Q. d. 'Pinnatifida' has bizarre leaves, like it belongs on a vine in an Amazonian rain forest. It too changes from orange to brown in autumn, but the best color is in spring with unfurling red-purple leaves.

Ginkgo biloba 'Tschi tschi'

Ginkgo biloba 'Tschi tschi'

Ginkgo biloba 'Variegata'

Ginkgo biloba 'Troll'

Ginkgo biloba 'Mariken'

Ginkgo biloba 'Mariken'

Ginkgo biloba 'Autumn Gold'

Ginkgo biloba 'Saratoga'

Ginkgo biloba 'Munchkin'

I know, I know that Ginkgo biloba had its origin in China, but many years ago it was introduced into Japan, and is commonly used as a street tree. I've never seen any cultivar that was colored differently than yellow, although some of the variegated selections can display two different shades of yellow. Dwarves such as 'Troll' and 'Mariken' are just as colorful as the larger-growing 'Autumn Gold' and 'Saratoga'. I once read emphatically from the editor of Sukiya Living, The Journal of Japanese Gardening that no Ginkgo was welcome in a real Japanese garden because they grew too large. When I wrote back I mentioned some dwarf cultivars, and 'Munchkin' being one that would never get too large. He addressed it again in the next issue, by claiming the term "dwarf" was almost always misused, and refused to be persuaded that one (or more) really are dwarf. I can barely get a 'Munchkin' two feet tall in ten years, so it is definitely dwarf. The experience with this imperious authority left a bad taste and I countered by dropping my subscription. Ha!

Cornus kousa 'Akatsuki'

Cornus kousa 'Akatsuki'

Cornus kousa 'Big Apple'
Cornus kousa 'KLVW'

Cornus kousa 'Summer Fun'

Cornus kousa is native to Japan and Korea, but was originally classified as Benthamia japonica by Siebold. Flower bracts range in color from white to red and make for an excellent spring show. Fall color can be equally spectacular, especially on the cultivar 'Summer Fun', where the green portion turns to purple, while the white edge evolves to pink. 'Akatsuki' is not as nice a variegation in spring and summer, nor is it a particularly strong grower, but it does display red or reddish flowers, and great autumn color. 'Big Apple' is fun for its large fruits while the foliage changes from green to orange and red by November. 'KLVW' is a clunky name – it stands for Kristin Lipka's Variegated Weeper – which is too much information for a cultivar name. Mr. Lipka named it for his daughter. The variegation isn't as attractive in spring and summer as 'Summer Fun', but 'KLVW' colors richly in fall. Actually all kousas, even seedlings, are famous for their autumn color, attested by my 500 rootstocks awaiting the grafting knife.

Berberis thunbergii 'Crimson Pygmy'
Berberis thunbergii 'Gold Pillar'

In the distant past we sold rooted cuttings of Berberis thunbergii 'Crimson Pygmy', which originated from the Japanese form of atropurpurea. 'Crimson Pygmy' was first raised in the Netherlands in 1942, but in hindsight they had more serious things to worry about with their neighbor to the east. We grew it by the thousands and sometimes provided 5,000 to a single customer. Twenty years ago the sales began to fade, so we quit cold turkey – and a good thing according to the employees who were sick of thorns. I bought a start of 'Gold Pillar' for the garden, but as it is patented I couldn't propagate it. Then I decided last winter, after a foot of snow, that my squashed plant wasn't such a great cultivar anyway. It did turn a pretty orange-red in fall, though, before the pillar was rendered procumbent.

Cercidiphyllum japonicum

Cercidiphyllum japonicum is a pretty species, but it can grow up to 150' tall. It thrives best in moist but well-drained soil, and if sited properly it can withstand full sun in Oregon. The leaves turn to pink or yellow or orange in autumn, and my theory is that the pink and yellow occur where there is sparse irrigation, and the orange when there is plenty. This is a casual observation at best, but it would be fun to put it to trial. I'm basing my guess with the pinkish-yellow color on the I-5 plantings near Olympia, Washington which never receive supplemental irrigation, and the orange fall color at my nursery and in other Northwest USA landscapes with irrigation. In any case the leaves give off a caramel scent when they bloom with the colors of fall. Cercidiphyllum magnificum is also from Japan, and it differs from C. japonicum by slightly larger leaves. Most nurserymen – including me – don't know what species we have with our various cultivars, and I am not sure why there is a need to classify two species instead of one anyway. Surprisingly, the magnificum species is much smaller, rarely exceeding 35' in height. It is endemic to central Honshu and grows at higher elevation than C. japonicum. The genus name is derived from its similarity to the Cercis genus, but it is known as Katsura in Japan. The Japanese family name of Katsura means "Osmanthus fragrans" or Cinnamomum cassia, and a popular animated character is named Kotonoha Katsura. The above photos of C. japonicum were taken at the Rhododendron Species Garden in Washington state last year, while the magnificum photo was taken in 2002 in a famous English garden, except I can't remember which one.

Deutzia gracilis 'Nikko'

Deutzia gracilis 'Nikko' is a wonderful shrub, and our oldest specimen is now 2' tall by 5' wide in 15 years. It is smothered in little white flowers in spring, then the narrow – hence the species name gracilis – leaves turn to dark purple in fall. According to the US National Arboretum, 'Nikko' was originally named Deutzia nakaiana from the Watanabe Nursery in Gotemba, Japan by former National Arboretum director John Creech and chief horticulturist Sylvester March in 1976. And the cultivar name 'Nikko' was coined by the Greenbank Nursery of England in 1977. I love the petite little shrub, partly because it reminds me of my visit to Nikko, Japan twelve years ago, where my wife and I practiced making children in the same hotel that was headquarters for Douglas McArthur after World War Two. Well, practice made perfect.

Hamamelis japonica 'Obtusata'

Hamamelis x intermedia 'Strawberries & Cream'

I have seen Hamamelis japonica 'Obtusata' only once, and that was in the Sir Harold Hillier Arboretum (photo above). The Missouri Botanical Garden lists it as var. obtusata, but anyway the autumn color is a fantastic butter yellow. Strangely the Hillier Manual of Trees and Shrubs doesn't even list it in the 2014 edition, while the Royal Horticultural Society lists it as Hamamelis japonica var. obtusata f. incarnata. I don't grow any cultivars of H. japonica, but the japonica x mollis hybrid known as x intermedia is well represented at Buchholz Nursery.

Abies veitchii 'Glauca'

Some Japanese conifers display great color, and not just in the fall, but throughout the entire year. Abies veitchii is normally green in foliage, but the cultivar 'Glauca' displays blue needles with silvery-white bands beneath. It is attractive when looking at it, for then it is mostly blue; but when you stand under a good-sized specimen, you see mostly silver. My start came from the Porterhowse Arboretum in Sandy, Oregon, and the photo above is from their tree. Abies veitchii was first discovered by J.G. Veitch on Mt. Fuji in 1860, but was introduced into cultivation by Charles Maries in 1879.

I'm pretty sure that the greatest number of species that I have grown at Buchholz Nursery have come from Japan, with China second probably. The Japanese connection provides many excellent trees and shrubs for our similar climates, and many of the species have a fascinating history about their introduction. The Japanese flora was certainly ripe for the plunder, and I think it caused no serious harm; science was advanced with the abundance of new taxa. So all is good with Japan. We like each other now, in spite of our animosity in the 1940's, and I think the growing of Japanese species has helped to heal our wounds. Ko ni chi wa to all.

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