Friday, July 17, 2015

China: Mother of Gardens

Lilium regale

I was in China last week, not literally but rather via the Flora Wonder Blog, when I discussed the great plant collector E.H. Wilson and his discovery of Lilium regale. He was caught in a landslide and nearly lost his leg, but when back in Boston he was fitted with a special boot and was able to walk for the next 20 years, albeit with his “lily limp.” It was Wilson who coined “China: Mother of Gardens,” and he and others collected plants that are now a significant part of western horticulture. Even my career is based on Asian exotics, as apparently enough American and Canadian gardeners like to feature them in their landscapes.

It is estimated – today, not in Wilson's time – that there exists some 31,000 native plant species in China, about a third more than in Canada and the United States*

*Similarly, in the Smokies there exists a greater number of species than in all of Europe.

Davidia involucrata
Davidia involucrata 'Sonoma'

If someone says “Quick! Name a Chinese plant species,” I would probably blurt out Davidia involucrata, commonly known as the “dove tree” or “handkerchief tree” due to the two long white bracts dangling around the purple globular female flower. The French missionary Armand David was the first westerner to see it in about 1870, but it was Wilson who collected large quantities of seed for his English employer, the Veitch Nursery in 1904. Davidia contains only one species, but it can be divided into two varieties: var. involucrata and var. vilmoriniana, with the latter having glabrous leaves and more elliptic seed. Davidia is related to Nyssa, with both in the Nyssaceae family.

Davidia involucrata 'Lady Sunshine'

Davidia involucrata 'Aya nishiki'

Davidia involucrata 'White Dust'

Davidia involucrata 'Kylee's Columnar'

Davidia involucrata 'Platt's Variegated'

Buchholz Nursery doesn't sell the straight Davidia involucrata, but rather cultivars of it. 'Sonoma' was selected* in California for its larger bract size, but another important characteristic is that it flowers at a young age, at times even on a one-year graft. It's a marvel to see a 6-7' tall tree loaded with up to 20 blossoms and 40 bracts. My favorite of the variegated cultivars is 'Lady Sunshine'. I price them a little bit high, but they sell instantly anyway. 'Aya nishiki' can be gorgeous, but it prefers the humid Japanese summers over the dry Oregon heat. 'White Dust' features green leaves variegated with subtle white portions, but I'm also partial to its reddish new growth. 'Kylee's Columnar' isn't all that columnar, but its stems are a little more slender than the type. 'Platt's Variegated' was of seed origin growing in the renowned garden of Jane Platt of Portland, Oregon. I saw the mature specimen one May and was struck by the variegation, but that was back when I didn't know much about Davidia. Later I learned that a bract is actually a modified leaf, and sometimes the tree expresses itself with a half-and-half appearance. I named and introduced 'Platt's Variegated' in my ignorance; but we no longer propagate it because a tree will have to be about 15 years old before the white coloration appears, too old to be practical. And by the way, I've never seen flowers yet on 'Lady Sunshine', and if one developed maybe I would miss it in the spectacular foliage. Or else, maybe it uses up all of its whiteness with the leaves and perhaps will never flower.

*In Hillier's Manual of Trees and Shrubs it says that 'Sonoma' was selected for its early flowering. That's not correct according to Polo de Lorenzo, owner of Sonoma Horticultural Nursery, the introducer who told me the surprising early flowering was just an added bonus beyond the bract size.

Paeonia lutea var. ludlowii

Paeonia lutea var. ludlowii seeds

Paeonia suffruticosa 'Rock's Variety'

Paeonia suffruticosa 'Rock's Variety'

Joseph Rock
The Paeonia genus is now characterized by gaudy hybrids with cutesipoo names like 'Cream Puff', 'Lemon Chiffon', 'Miss America', 'Shirley Temple' etc. I think they're someone else's garden. However there are a few species that I like: ludlowii, mlokosewitschii, delavayi and rockii, the latter perhaps my favorite. Rockii was named for the Austrian-American linguist and botanist Joseph Rock who found it in the mountains of western China. But not so fast, since the botanists of today classify it as P. suffruticosa 'Rock's Variety'. I have also seen this “Moutan peony” listed as P. suffruticosa ssp. rockii. The semi-double white flowers feature a maroon blotch at the base of each petal. Joseph Rock (1884-1962) was a rather flamboyant plant collector who liked to bathe in the evening in his portable Abercrombie and Fitch bathtub. He was in the same area of Yunnan where I have been, and in his career he collected plants for the U.S. Department of Agriculture, the Arnold Arboretum and others. He once measured a mountain peak as taller than Mt. Everest and published his discovery. Oops...

Acer davidii

Acer davidii 'Serpentine'

Acer davidii originates from central and western China, and according to De Beaulieu in An Illustrated Guide to Maples, it was “introduced from the provinces of Hubei and Sichuan to England in 1879 by Charles Maries for Veitch Nursery. Plants were imported to Europe from Yunnan by George Forrest and Francis Kingdon-Ward and from Hubei by Ernest H. Wilson.” At Buchholz Nursery we root cuttings or purchase seedlings of A. davidii as understock for the davidii cultivar 'Serpentine', as well as for cultivars of other species in the Section Macrantha. 'Serpentine' was introduced by Hooftman of The Netherlands in 1976. It is a smaller tree than most of the other davidii cultivars, but the best part for me is the purple-red trunk with white stripes. Good job Hooftman.

Disporum longistylum 'Night Heron'

Disporum longistylum is a Chinese species name that has replaced the specific name cantoniense, and we grow the cultivar 'Night Heron'. Dan Hinkley, former owner of Heronswood Nursery, collected seed from Sichuan Province and his packet certainly contained a winner. 'Night Heron' is a lithesome creature with black-purple shoots rising from the soil in spring. Flowers appear in April, a pale green color like lima beans, but they contrast nicely with the delicious stem and leaves. The “Night Heron” name (by Hinkley) was fantastic, as the nodding flower stems look very much like the Black-crowned night heron, Nycticorax nycticorax. It prefers rich humus soil with light shade and is hardy to -20 degrees F, USDA zone 5. An added bonus is that the flowers are followed by ornamental purple-black berries. The species is a wonderful rhyzomous perennial with the sweet common name of “Chinese Fairy Bells.”

Abies squamata
Acer griseum

Acer griseum in October

Continuing with the theme China: Mother of Gardens, there are two tree species – Abies squamata and Acer griseum – that share similar outstanding exfoliating bark. Both species are nice enough on their own, even without the bark, for A. squamata is handsome for its deep blue-green foliage with shiny white buds and purple cones, and A. griseum for its fuzzy greyish new buds and superb orange-red fall foliage color. But add in the ornamental bark and both vie for the title of the “perfect tree.” Acer griseum has become almost common in Oregon landscapes, and on a number of boulevards it is used as a street tree. There, it looks stately and elegant. Abies squamata is far more rare, and in fact I have never seen it used in any American landscape, and actually only at Buchholz Nursery and in a few high-end European arboreta. My career-long desire to see both species in the wild may or may not happen, but if it does it would be convenienced by the fact that both can be found in Sichuan, China. How appropriate that E.H. “Chinese” Wilson stumbled upon Acer griseum – in spite of his Davidia involucrata frenzy in 1901 – and Abies squamata in 1910, and thus introduced the two most elegant “bark-trees” that western horticulture has ever seen. I will admit that Abies squamata is not for everyone, as this Chinese species holds the highest-altitude record for any Abies in the world, and it might not be happy in your low-altitude climate or in your cruel heat and high humidity. This winter we will propagate Abies squamata onto Abies firma, the rootstock a Japanese low-land species renowned for tolerating heat and humidity. While I may never see A. squamata in the wild, I will still attempt to bring a few starts into American gardens. But don't thank me – I have done only a little – but give thanks to Chinese Wilson for doing the hard part.

Acer pentaphyllum

Acer pentaphyllum: ah, a species highly revered by me for its green linearlobum leaves, and for its wonderful yellow-to-orange-to-red autumn foliage. Sadly, not quite hardy in some Oregon winters, I grow the species in my “tropical” GH20. At one point in my career I had more (in number) for sale than the number of individual survivors left in China. That always seemed kind of weird to me. One can root the species via summer soft-wood cuttings, or propagate by seed, or fantastically by grafting onto the American species, Acer rubrum. I once grafted A. pentaphyllum onto A. rubrum – and it produced an accommodating graft union. Later I purposely left it outside during a harsh winter, and the rubrum rootstock shot up vigorous green shoot-growth in spring while the pentaphyllum withered and died. A most useful (for my career) Acer scion-to-compatible-rootstock account was given by JD Vertrees in the 1980's and I give you his research-and-conclusions (below) during a speech to the International Propagators Society Western Region's meeting in Beaverton Oregon. Sadly, Vertrees was cut very short as the proceedings were terminated early during his presentation due to conflict with the lunch hour. I went home and fumed because my expensive ticket to more Acer knowledge was diminished due to cold lasagna and a burpy cucumber-salad lunch.

Acer scion Acer understock choice
aidzuense ginnala, tataricum
amplum platanoides
buergerianum cvs. buergerianum
campbellii palmatum
campestre cvs. campestre
capillipes davidii
cappadocicum platanoides, campestre
circinatum cvs. palmatum
coreaceum pseudoplatanus
craibianum crataegifolium, davidii
(creticum) sempervirens Which see
davidii cvs. davidii
diabolicum rubrum (L)
divergens campestre
erianthum palmatum (L)
flabellatum palmatum
forrestii davidii
franchettii pseudoplatanus (P) rubrum (L)
fulvescens platanoides
ginnala cvs. ginnala, tataricum
griseum griseum (L) rubrum (L)
grosseri davidii
heldreichii pseudoplatanus
hookeri davidii (L) crataegifolium (L)
hyrcanum pseudoplatanus
ibericum campestre (L) monspessulanum
japonicum cvs. palmatum
kawakamii davidii
laevigatum palmatum
lobelii platanoides
macrophyllum cvs. macrophyllum
mandshuricum rubrum (L) buergerianum (L) griseum (P)
maximowiczianum (nikoense) rubrum (L) buergerianum (L) griseum (P)
maximowiczii davidii
mayrii platanoides
micranthum davidii
miyabei platanoides, campestre
mono cvs. truncatum ssp. mono, platanoides
monspessulanum campestre
(morrisonense) rubescens Which see
(nikoense) maximowiczianum Which see
oblongum buergerianum
obtusifolium (syriacum) campestre
oliverianum palmatum
(orientale) sempervirens Which see
paxii buergerianum
pectinatum davidii
pensylvanicum cvs. davidii, pensylvanicum
pentaphyllum pseudoplatanus, saccharinum, saccharum, rubrum
platanoides cvs. platanoides
pseudoplatanus cvs. pseudoplatanus
pseudosieboldianum cvs. palmatum
pycnanthum rubrum
rubescens (morrisonense) davidii
rubrum cvs. rubrum
rufinerve cvs. davidii
saccharinum cvs. saccharinum
saccharum cvs. saccharum
seminovii ginnala
sempervirens (orientale) campestre
shirasawanum cvs. palmatum
sieboldianum cvs. palmatum
sterculianum pseudoplatanus
(syriacum) obtusifolium Which see
takeshimense palmatum
taronense davidii
tataricum ginnala, tataricum
tegmentosum davidii
tenuifolium palmatum
triflorum rubrum, griseum (P), buergerianum (L)
truncatum truncatum ssp. mono, platanoides
turcomanicum campestre
tschonoskii cvs. davidii
wardii davidii (L) palmatum (L)
wilsonii palmatum

Picea asperata

Wilson collected a couple of Chinese Picea species, asperata and brachytyla, and I have grown both of them although not for much profit. The P. brachytyla is a beautiful semi-weeping tree and I had a fine specimen which was much admired by visitors. I discontinued propagating it due to poor sales so I only had my one specimen. Had, as in one morning I was dismayed to see that it crashed to the ground after a night of rain and howling winds. Sadly I never even got around to photographing the tree. Picea asperata is a medium-sized tree and can be considered the Asian counterpart to the European Picea abies. Wilson collected it in 1910 from western China, but most would describe it as a BIO plant, that is of Botanical Interest Only. I have no idea where the photo above was taken, but it certainly wasn't on my property. At the beginning of my career I germinated asperata for the heck of it, and I selected out the one with the most blue foliage. I named it 'China Blue', then eventually sold the original; but fortunately I saved a few starts from it and one specimen now resides in my Conifer Field.

Pinus armandii

Pinus armandii is a medium-sized, good-looking species with long glaucous needles that give it a weeping look. It was named after Armand David, and I've always thought it strange that a species could be named after someone's first name, as with this pine, and another species named after his last name, as in Acer davidii. Similarly we have Abies ernestii and Magnolia wilsonii, both honoring Ernest H. Wilson. Anyway the cone photo above was taken at the Camellia monastery just outside of Lijiang, Yunnan and the Chinese monk was no doubt piling up the cones to dry for the precious nutlets contained therein. We also used to grow Pinus armandii x Pinus koraiensis which appears intermediate between the species. I know of no cultivars of Pinus armandii, but let me know if you do.

Pinus morrisonicola 'BR007 Wilson'

I grow a Pinus morrisonicola that was designated BR007 Wilson. During Wilson's latter years he explored in Taiwan, certainly with less zeal than in his younger days due to his lily limp. My start came from a rogue botanist who was anxious to split as many species as possible so he could put his name on one of the divided. In any case, I never knew where any of his scionwood came from, or if his identification was correct. One would surmise that the morrisonicola was something that Wilson collected, and at that time the Englishman was working for the Arnold Arboretum. He collected it either on or near Mt. Morrison, I assume, but I don't know at what elevation. Mt. Morrison was first observed by W. Morrison, captain of the American ship SS Alexander and he recorded it in his naval log (1857); but the Chinese already had their own name of yushan, which translates as “Jade Mountain.” It is located in the middle of the island and it soars to 3952 m (12,966'), and is famous for its wealth of flora and fauna.* Yushan once was under the ocean, but shifting tectonic plates lifted up a mountainous ridge that runs north to south along the entire length of the island. The vegetation ranges from evergreen broadleaves at the bottom to deciduous and coniferous forests higher up, with only mosses, liverworts and some grass at the top.

*Yushan National Park is nicknamed “The Ark” by scientists since it contains so many of Taiwan's rare species.

Dipteronia sinensis

I used to grow Dipteronia sinensis, not that I particularly admired the species, but for the fact that it is a member of the Sapindaceae Family (soapberry family) and therefore related to the Acer genus. I felt somewhat obligated that I should grow some, and they would be purchased by gardeners who likewise felt obligated to buy them. But it didn't happen. I kept my one last tree planted at Flora Farm where it floundered for about five years...then eventually died, and now I don't have Dipteronia anymore, nor know where I could acquire another. Thanks for the memories. Like Acer, Dipteronia is a deciduous flowering shrub or small tree, and is clothed in opposite pinnate leaves as you can see from the photo above. The seed is round and contains two flat nutlets and the wing can turn to red when ripe. The name Dipteronia is derived from di for “two” and pteron for “wings” due to wings on both sides of the seed.

Tetracentron sinense

Another nice Chinese species, Tetracentron sinense, is like the Dipteronia mentioned above, where neither is simply a BIO plant, but rather something worth growing if space allows. The Tetracentron is a medium-sized deciduous tree with heart-shaped green leaves that are red-tinted when young. It is in the Trochodendraceae Family and is native to the southern part of China and the eastern Himalaya, but to some-of-us it looks like a Cercidiphyllum on steroids. For the (fossil) record Tetracentron was once found in Alaska, Washington state and Iceland. I would recommend anyone fascinated beyond my account to visit a splendid specimen in the Rhododendron Species Garden in Federal Way, Washington, which is of Sichuan origin. The genus was first described by Daniel Oliver, the Keeper of Kew from 1860-1890. I have a specimen of the Chinese Acer oliverianum which honors the same botanist. A cultivar of A. oliverianum that I covet is 'Nakahara beni', and I know a couple of Boys who have it in North Carolina!

So, there you have a grab-bag of Chinese plants, all worthy of attention. Some will always be rare and under-used, while others have become over-abundant. I can't hold your hand beyond this point; you must research and trial on your own now.

Ah, how interesting! From my cyber-world records I see that most of you reading this blog have returned to the limpid-lithe photo of Disporum l. 'Night Heron', and what a sexy selection it is!

"Remember: it is ok to form relationships with your plants!"

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