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| Acer palmatum |
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| Acer japonicum |
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| Acer shirasawanum |
The islands of Japan are blessed with a sizable number (about 20) of
Acer (maple) species, some of which you have probably never seen.
Most growers, both commercial and the hobbyist, are quite familiar
with the Big Three: with Acer palmatum certainly, and to a
lesser extent Acer japonicum and Acer shirasawanum. All three are
compatible (as rootstock-to-scions) with each other, although there
are other species that would combine as well (for example the Chinese
Acer oliverianum).
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| Maple grafts |
Early in my career I collected and propagated cultivars
(cultivated variants), and I assumed at the time that the three
species were sufficient to cover what ever was to be the future of
Buchholz Nursery. The late maple guru and author, J.D. Vertrees, took
an interest in my company, which pleased me greatly. Once he asked if
I was interested in other species of maple, to which I replied, “Not
particularly.” He responded, “Well, you will.” Vertrees wasn't
aware, apparently, that my mental faculties were at their limit with
just three species, and I blamed the “full sponge theory” for my
limitations, that my brain couldn't absorb any more information
without deleting some of what I had already processed. Besides, I was
obsessed with money...because I didn't have any, and all of my
efforts were geared toward financial survival. Well, Vertrees was
right and I eventually began to study and propagate other species, to
my great enjoyment. But I was right too, in the sense that the Big
Three have accounted for over 95% of my career's maple sales.
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| Carl Peter Thunberg |
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| Thunberg's Flora Japonica |
The great botanist Linnaeus coined the genus name of
Acer
which is Latin for “sharp,” apparently in reference to the
sharply pointed lobes on some species. A student, or “disciple”
of Linnaeus was Carl Peter Thunberg (1743-1828), a Swedish naturalist
who eventually traveled to Japan and produced his
Flora Japonica
in 1784. His sojourns were limited but he was the first to describe
Acer palmatum in 1820, a species also found growing in eastern China,
Korea and Taiwan. Acer japonicum followed in 1864, although Thunberg
was long gone by then.
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| Gen ichi Koidzumi |
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Peter Gregory admiring an Acer circinatum witches broom
at Portland, Oregon's Hoyt Arboretum |
If you investigate the history of the last (of these three) specific
epithets, credit for Acer shirasawanum goes to “Koidz,”
who describes the species as, “A small bushy tree or large shrub
of elegant habit...” Since I have propagated and sold many
thousands of these “bushy trees,” I'm naturally curious to know
about the specific namer. Gen ichi Koidzumi (1883-1953) was a
Japanese botanist who specialized in the Rosaceae family besides
maples, and who could argue for a better, though unrelated,
combination? He was Professor of Plant Taxonomy at Kyoto University
and helped to found the journal Acta Phytotaxonomica et
Geobotanica in 1932, and also worked on the Revisio
Aceracearum Japonicarum in 1913. With fellow botanist Takenoshin
Nakai he compiled Trees and Shrubs Indigenous in Japan Proper
in 1927. Though the intellectual held university credentials, I
wonder what he was really like in the garden or field. Some of these
“professors” are/were insufferable and amateurs such as I have
learned to give them wide berth. Others have dirt under their
fingernails and are primarily motivated by instilling enthusiasm for
botany with children and the rustic layman. I fall somewhere between
these two groups, and I recognize and appreciate the efforts of Acer
experts such as the late Englishman Peter Gregory, author of Japanese
Maples (4th edition), as a down-to-earth apostle for
the Acer genus.
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| Acer pictum 'Hoshi yadori' |
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| Acer pictum 'Usu gumo' |
When Vertrees quizzed me about additional Acer species, at the time
we were standing near Acer pictum 'Hoshi yadori', a large-leafed
species of A. pictum, and a cultivar with cream-white splashed or
dotted (sunago fu) on the green bat-wing-like green leaves.
Honestly I didn't care for any of it at the time and I still don't.
Acer pictum 'Usu gumo' is more my type, and it's a colorful, compact
variegated selection that has never been difficult to sell. Usu
is Japanese for “thin” and gumo means “spider” or
“cloud.” With the maple in question, “thin cloud” seems an
appropriate name, however the network of veins on the leaf resembles
a spider-web pattern.
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| Acer pictum 'Usu gumo' |
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| Acer pictum 'Usu gumo' |
Vertrees describes 'Usu gumo' as “difficult to propagate and not
widely known in collections.” I've done my part to make it
available, using Acer truncatum as rootstock, and I consider it as
“easy” to graft as any maple cultivar if one begins with healthy
rootstock and young, vigorous scions – the type that you'll find on
five-year-old plants grown in containers that are pushed in a
protective greenhouse. I don't want to come across as dismissive (or
sacrilegious) about the Vertrees experience, but I regret that we
didn't have more time together to share our propagation experiences.
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| Map of Sakhalin Island |
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| Ainu people of Japan |
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| Acer truncatum |
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| Acer truncatum |
Acer truncatum (“Shantung maple”) is occasionally grouped
with “Japanese maples” because the Chinese native is closely
related to Acer pictum, and because it occurs on Sakhalin Island
which is located just north of Hokkaido, Japan, a territory that
Russia currently controls through its military power, but a land that
contains remnants of the pre-Japanese native Ainu people, and was
first settled by Japanese fishermen on its southern coast. Acer
truncatum is a tough, hardy, small deciduous tree that is championed
by Metro Maples Nursery in Fort Worth, Texas where it performs
admirably in that hell-hole environment. The species was named by
Alexander von Bunge (1803-1890) (of Pinus bungeana fame) who was
actually born in Kiev, Ukraine, which likewise the Russians now claim
to own.
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| Acer buergerianum |
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| Acer buergerianum 'Mino yatsubusa' |
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| Acer buergerianum subsp. ningpoense |
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| Acer buergerianum subsp. ningpoense |
Acer buergerianum (“Trident maple”) is another Chinese
species that many assume to be a Japanese native, but only because it
is widely cultivated in the “Land of the Rising Sun.” The
cumbersome specific epithet honors J. Buerger (1804-1858) who
discovered the maple, but it's far easier to call it the “Trident
maple” due to its normal appearance with three lobes. There's no
maple species, in my experience, that out-shines the Trident for fall
color, and with the dwarf cultivar 'Mino yatsubusa' you get green,
yellow, orange, red and purple, often at the same time. A subspecies
of Acer buergerianum is ningpoense, coming from Ningpo (or
today, Ningbo), an area in Zhejiang, China. It is probably a zone
less cold tolerant (to USDA zone 6, -10 F) than other locations of
the Trident. De Beaulieu throws me into some confusion when he
describes the leaves of the subspecies as being “two-lobed,” when
the photos above clearly demonstrate three lobes. Furthermore, De B
states that “On the young shoots the red leaves are in groups of
three, with a larger leaf in the middle...” I've not seen any
such grouping, so I'm left to wonder if my version is accurate. This
is where the Flora Wonder Blog should become a two-way street, a
forum, so I would appreciate if someone could set me straight,
thanks.
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| Philipp von Siebold |
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| Siebold's Flora Japonica |
Philipp von Siebold (1796-1866) is no stranger to the Flora Wonder
Blog, and the German physician/botanist was known for his studies of
the Japanese flora and fauna. A maple was named in his honor, Acer
sieboldianum, by botanist FAW Miquel. Siebold also penned a Flora
Japonica, as did Thunberg earlier, with the help of another
German botanist, Joseph Gerhard Zuccarini (1797-1848). The work
appeared in 1835 but it was not completed in Siebold's lifetime, and
after his death it was completed by Miquel.
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| Acer sieboldianum 'Sode no uchi' |
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| Acer tenuifolium 'Keikan zan' |
My experience with Acer sieboldianum is limited, and I have never
grown the straight species, only a few cultivars. The first I
collected was 'Sode no uchi', a slow-growing compact form. However,
Japanese author Masayoshi Yano in his Book for Maples suspects
that it more correctly belongs to Acer tenuifolium. The latter is
difficult to find in the literature, and not as a recognized species,
but as a variety (var.) of Acer shirasawanum, at least
according to De Beaulieu in his An Illustrated Guide to Maples
(Timber Press, 2003). I know of only one other cultivar of A.
tenuifolium, 'Keikan zan', which certainly looks like a
smaller-leaved version of the “Full Moon maple,” Acer
shirasawanum. The reader probably grows weary at this point, and must
wonder why any of this matters, to which I have no answer.
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| Acer sieboldianum 'Mequel' |
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| Acer sieboldianum 'Kumoi nishiki' |
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| Acer sieboldianum 'Mikasa nishiki' |
The recognized cultivars of A. sieboldianum that I have grown include
the wonderfully variegated 'Kumoi nishiki', 'Microphyllum' with
smallish leaves, 'Mikasa yama' with its narrow canopy (at least for
me) and the spreading, semi-weeping 'Seki no kegon'. I have also seen
a variegated selection in Yano's collection, 'Mikasa nishiki', which
was colorful in a pot in semi-shade. Another sieboldianum cultivar
growing at Yano's is 'Mequel', but that was seen in late fall, with
only one vigorous whip-shoot still with leaves; the only reason I
mention 'Mequel is because I wonder if that is a misspelling of
Miquel, the German botanist who finished Siebold's
Flora
Japonica. Hmm...
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| Acer pseudosieboldianum |
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| Acer pseudosieboldianum |
Specific
epithets are given to plants to document particular attributes, such
as alpina
for those growing in alpine regions, alba
for white colour, thunbergii
to commemorate a plantsman/botanist, nana
for a dwarf habit etc. I dislike epithets that allude to other
plants, such as with Acer pseudosieboldianum, which would means the
“false” Acer sieboldianum. I don't know – it just seems like
the naming botanist took a cheap shortcut. Acer sieboldianum was
introduced to the West in about 1880, while the similar Acer
pseudosieboldianum was named by botanist Pax in 1904. Stuff like that
can be confusing to the amateur gardener, if not the professional
grower also. Come up with something original or leave the naming to
another. In any case Hillier in Manual
of Trees and Shrubs
(2019) describes Acer pseudosieboldianum as “a
very graceful, large shrub or small tree of spreading habit...”
My experience differs, for those I have grown are usually narrow and
straggly, kind of like our native “Vine maple,” Acer circinatum,
and where growing in clumps is the best method to deal with the
unshapeliness. Mark Krautmann of Heritage Seedlings, Oregon, has
grown thousands of seedlings of A. pseudosieboldianum, commonly known
as the “Korean maple,” and he describes it as a “wild species”
that hasn't been grown long enough to settle into horticulture.
Anyway, that's what he said 10 years ago, even though I don't quite
follow that logic. The outstanding feature in my opinion is the
vibrant autumn colours and a very important attribute is that the
species is cold hardy to -30 F, USDA zone 4. The hardiness has been
promoted in recent years with selections crossed with Acer palmatum,
and I've seen the hybrids thriving in cold places such as in northern
Montana, where the premier garden center in Kalispell carried no A.
palmatums at all, only the hardy hybrids.
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| Acer carpinifolium |
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| Acer carpinifolium |
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| Acer carpinifolium 'Esveld Select' |
Another Japanese species that alludes to a different plant is Acer
carpinifolium, the “Hornbeam maple.” This small-to-medium-size
tree was introduced from Japan in 1879 by Charles Maries who
collected for the English Veitch Nursery firm. I've heard comments
like, “That sure doesn't look like a maple to me!,” to which I
love to point out a branch with the tell-tale maple samaras. Acer
carpinifolium is also hardy to -30 F, or so they say – but I would
sooner jump off the bridge than experience temperatures that cold in
my Oregon nursery. I have only one specimen left at Flora Farm, but
prior to that I grew a couple hundred seedlings which I found
difficult to sell. I suppose because the flowers are insignificant
and the autumn colour is yellow-to-brown, a subtle and warm, but
uncommercial colour. One regret of my career is that I was never able
to acquire the boldly serrated selection, Acer carpinifolium 'Esveld
Select', discovered and named by the renowned maple nursery in
Boskoop, Holland. Someone, please, treat me to a surprise!
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| Acer crataegifolium 'Eiga nishiki' |
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| Acer crataegifolium 'Meuri ofu' |
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| Acer crataegifolium 'Meuri ofu' |
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| Acer crataegifolium 'Veitchii' |
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| Acer crataegifolium 'Veitchii' |
Yet
another allusive specific epithet belongs to Acer crataegifolium, the
“Hawthorne maple.” It too was collected by Charles Maries from
Japan in 1879. Crataegus leaves are without much merit in my opinion,
but the maple leaves of the Acer species don't resemble any Hawthorne
species that I've ever seen anyway. What a shame to be saddled with a
difficult name to pronounce and spell, especially since the maple is
daintily attractive to me. There are a few variegated cultivars that
I have propagated – 'Eiga nishiki', 'Meuri ofu' and 'Veitchii',
with the latter two looking similar. What I find interesting is that
the species was introduced in 1879, while the cultivar 'Veitchii' was
introduced just two years later in 1881. Of course the “Veitch”
name was chosen to honor the sponsoring English firm that sent Maries
to Japan in the first place. I doubt that in just two years a
variegated form could have been selected in England, and so the
variegated clone must have been of Japanese origin. Did Maries
discover it, or was there a Japanese grower who should get the
credit? Did Veitch in England receive the one and only seedling
specimen, or were there others in production? Hillier describes
'Veichii': “Leaves
heavily mottled with white and pink, brilliant pink and purple in
autumn.”
One can produce 'Veitchii' from softwood cuttings in summer under
mist, but for a stronger-growing tree the use of Acer davidii, or
another species in the Macrantha section, is recommended. Brian
Humphrey in his The
Benchgrafter's Handbook
(CRC Press, 2019) mentions that “Acer
palmatum is also said to produce a compatible union.”
I wonder about that comment since it seems unlikely to this
nurseryman, but for the sake of the narrative we grafted a flat of 25
yesterday and I'll report my results in a year or two.
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| Acer crataegifolium 'Veitchii' |
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| Masayoshi yano |
I
had an interesting occurrence with the aforementioned A.c. 'Veitchii',
that an older specimen – always heavily variegated – was
transplanted from the nursery to Flora Farm. Some digging trauma for
a ball-and-burlap tree is normal, but usually it's a minor set-back
and the victim will recover in a year or two. My specimen survived,
but in spring it leafed out with just green leaves and no
variegation. Then a 2nd
and 3rd
year passed, also without variegation. The famous Japanese maple
guy, Masayoshi Yano, approached my tree with curiosity. After eyeing
the tree he noticed the label and his face registered complete
confusion. Why was there a 'Veitchii' with no colour? I recounted the
digging-trauma theory but he still looked dubious, and to this day I
imagine he viewed my credentials with suspicion. But in the 4th
spring after the transplantment the foliage emerged heavily
variegated again, and I wanted to drag Yano back to Oregon to prove
that my tree was indeed correctly identified. So: 3 years with no
colourful variegation, the 4th
with spectacular colour...but the 5th
year nothing leafed out because the tree was dead. I felt that
'Veitchii' was ungrateful after all my perserverance. All of that was
10 years ago and I've been unable to source a replacement.
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| Acer micranthum |
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| Acer micranthum |
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| Acer micranthum from Westonbirt Arboretum |
One
of my favorite of all Japanese maple species is Acer micranthum,
commonly called the “small-flowered maple” as the epithet
micranthus
means “having small flowers.” As with Acer crataegifolium, Acer
micranthum can be rooted by cuttings, or by grafting on anything in
the section Micrantha. A beautiful photo of the wonderful Acer
micranthum in autumn (at Westonbirt Arboretum in England) is found on
page 198 in De Beaulieu's illustrated guide, and in fact that's the
very tree that got me hooked on the species. I was with Peter Gregory
who was then head of the arboretum, and I remember his eyes sparkling
with delight as he showed off its pinkish-red seed clusters. In
spring the small pale-yellow flowers develop into tiny seeds, the
smallest in the Acer genus. Everything about the tree is dainty, yet
it is supposedly cold hardy to -20 F, USDA zone 5. I have grown it in
full sun, the only problem being a slightly burnt trunk when the tree
was young and the summer temperature exceeded 100 F. Acer micranthum
was introduced to Europe about 1880, although it was described by
Siebold and Zuccarini in 1845.
I'll
pause for now, about halfway through my Maple
Species from Japan,
and hopefully I can continue next week with a review of other
wonderful species.
