Acer pentaphyllum
By William A. McNamara
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Almost daily we hear of species on the brink
of extinction. \X!hereas a few are familiar
a'nimals seen in zoos, on television or in
magazines, most are unfamiliar plants and
animals, often in some far corner of the
world. Many·eminent biologists say tha t we
are in the midst of a sixth mass extinction
that bega n \.vith the advent of agriculture
about 10,000 yea rs ago, enabling our
popula tion to increase and eventually inhabit
most of the earth.
As our population
continues to grow at an accelerating rate,
especially in the last fifty years, so has the
rate of extinctions. Unlike the previous five
mass extinctions, this one is driven by the
impact of a single species - Homo sapiens.
\Xfe humans are increasingly altering and
destroying habitats in both subtle and
obvious ways. It is difficult to calcula te tl1e
effect on tl1e world's biodiversity, but mos t
scientists concur that it is more than
substantiaL Some estimates put the current
extinction rate as high as 27,000 species a
yea r or 3 every hour (Park 2001). As I look
Ciut my window in bucolic Sonoma Valley at
the distant oaks, redwoods and Douglas firs,
it is difficult to comprehend such loss. For
this horticulturist though, nothing brings
home the message as clearly as a visit to the
last remaining stand of a rare tree ilit I have
known a nd admired for years.
almost thirty years in China, funded by various American organizations, collecting plant
specimens and studying the cultures of the
inhabitants of ilie mountainous regions of
Yunnan, Sichuan and Gansu.
U nder his collection number 17,819, he wrote
. tl1a t tl1is species was ten meters high and was
growing at an elevation of 3,050 meters, between Baurong and 'Kulu, west of the Yalung
River (Yalong Jiang). It was named and described in 1931 by Professor Diels, the Director of the German State Bota nic Garden at
Berlin-Dahlem. Three trees a t Strybing Arbo- ·
return in San Francisco were presumed to be
the only known survivors from Rock's discovery. One tree, possibly the parent of the
otl1er two, appeared to be older than the others and had a fifteen-centimeter trunk, while
the other two had trunks of eight- to tencentimeters. All three ha d died by 1991, one
girdled by a squirrel, and the others from root
rot. Strybing's records state that the origin
was unknown, but that they may have come
from UC Berkeley Botanical Garden. Berkeley does have an accession record for Acer
pentaphyllum (#38.996) saying it was from
Rock, but it does not mention a Rock collection number. The note also differs slightly by
. stating that the location was "opposite
Baurong in lateral gorge ofYalung River" and
that it was collected at an altitude of 6,000
feet, much lower tha n Rock's. 3,050 meters
(10,000 feet). \X!he ther this is an error or
represents a second collection by Rock is
unclear. Unfortunately, Berkeley has no re-.
cord of what happened to their accession and
currently have no trees of this species it its
collection.
Like many enthusiastic nursetymen, maples
became an early interest of mine. I admired
their many leaf shapes, graceful branching,
and exceptional fall color. I was intrigued by
the more than 150 species and ilie many
cultivars, especially of Japanese maples (Acer
palmatum). However, it was another Asian
maple that slowly emerged as my favorite.
\\lhether it was the unusual deeply cut lobes, It has been widely publicized that all Acer
or the rarity of it in cultiva tion and in the pentaphyllum in cultivation in North America
wild, Acer pentaplyllum captured my imagina- . are from Rock's trees at Strybing Arboretum.
r\pparently, Strybing's trees rarely set seed but
tion. \\lith five, occasionally seven, na rrow
some were successfully. propagated from scilea flets divided to ilie base, it is quite distinct
ons. Renowned nurseryman Toichi Domoto
from other maples. The leaflets have acumi
successfully grafted scions onto seedlings of
nate tips a nd are usually seven to ten centisugar maple (Acer saccha rum) and distributed
meters long and less that one centimeter
them. This is evidently tl1e origin of the tree
wide; the leaves have red petioles. Although
at Western Hills Nursery in Occidental, which
it can be a tree as high as ten meters, it usuproduces large quantities of viable seed and is
ally grows as a large shrub to three or four
now over ten meters tall. Other trees grafted
meters.
Fall color ranges from yellow to
cnmson.
The terminal flower clusters are ·by Domoto also produced viable seed and
yellow. Though not considered particula rly
from these he dis tri.buted seedlings. All Acer
hard y, young trees have survived 14 degrees pentaphyllum in cultivation today, \vith one
Fa hrenheit (-10 Celsius) in Sonoma, Califorexception, appea r to trace their origin to Donia during the freeze of December 1990.
mota, Western Hills, and ultimately Strybing
A rboretum.
Although this maple is now .
listed in severalnursety catalogues, it remains
During an expedition sponsored by th e Navery rare in cultivation. .
tional Geographic Society in 1929, Joseph
Rock discovered Acer pentaphyl/um in southA n interesting article in THE PLANTSMAN
western Sichuan near the small Tibetan town
in 1991 by Dr. E. E. Kemp puts a curious
of Muli. Rock, an eccentric gifted selfnvist on tl1e origin of Strybing's legendaty
trained linguist-botanist from Austria, spent
Fall color on a young Acer penta phyllum
trees. Kemp was curator of The Royal Botanic Gardens, Edinburgh, from 1950 to
1971. He argues quite convincingly that,
although an Acer pentaplryllum may have made
its way to Strybing from Rock, · it did not
originate from his 1929 discovery. Kemp
states that Rock's collection in 1929 could
not have produced plants, as the collection
date was July 8, too early for seed to be viable. An examination of Rock's herbarium
specimen furthe· confirmed this, as did the
lack of any records of plants ongtnatlng
from the 1929 discovery. Kemp then relates
a chance meeting with Rock in July of 1939
at the German State Botanic Garden at Berlin-Dahlem, whereupon Rock approached
him wiili three small seedlings of Acer pentaplryllum under his arm. Rock presented him
wiili one of them asking him to take good
care of it at Edinburgh, adding, "it is very
rare '. Unfortunately, the tree only survived
a few years. Although Kemp initially assumed that the tree had been collected by
Rock, he later concluded that the tree must
have come from the well-known and highly
respected Chinese professor T. T. Yu. Yu
had collected herbarium specimens of A.-er
pentaplryllum on November 2, 1937 near Muli
and distributed these to several institutions
including the Royal Botanic Gardens at Edinburgh. The specimen there has many mature seeds, so it is quite possible that the
specimens sent elsewhere did as well. Rock
conceivably had· three trees wiili him iliat
had germinated from surplus seeds in Germa ny and wanted to give iliem go'od homes.
Kemp goes on to describe a visit to Strybing
A rboretum in 1966 with former director J.
Brydon. At that time, Strybing apparently
had only one tree of Acer pentaplryllttm. He
told Brydon that Strybing's tree must have
been one of the three that Rock had in 1939
and. was probably 'given to Strybing's first
director, Erich Walther, by Rock himself.
Rock knew and admired Walther's skills as a
plantsman. Perhaps this, then, is the reason
for the confusion.
Strybing's tree was
probably from Rock via Germany, but from·
Yu's collection in 1937, and not .from seed
collected by Rock when he discovered the
tree in 1929.
When I had the opportunity to travel to
western Sichuan, I wondered whether I
would have a chance to see this rare maple
in the wild. Little did I know that it would
take me fifteen journeys before I would find any. During my first visit to Sichuan in 1988, I learned, from our hosts at the Chinese Academy of
Sciences in Chengdu, tha t some trees of Acer pentap!iJ IIum occurred in a remote area
south of the small town of Jiulong, a village not on our itinerary a nd not yet open
to foreigners. Jiulong lies north of Muli and straddles the Jiulong River, surrounded by heavily forested mountains a bout seventy kilometers southwest of
Gongga Shan (:tviinya Konka), Sichuan's highes t moun tain at 7,556 meters. Three
yea rs later, in the fall of 1991, with special permits we traveled to the still closed
area of Jiulong. We had planned to collect specimens south and west of Jiulong.
U nfortunately, a landslide had destroyed the road west and the road sou th had been
washed away by heavy summer rains, ending any hope of seeing the trees that yea r.
In the spring of 1992, Dr. Yin Kaipu of the Chengdu Institute of Biology surprised
me with a gift of seeds of several different trees from weste rn Sichuan. Included
a mong them was a small packet of Acer pentapi!J IIttm seeds. After he told me that
they had been collected from the wild stand south of Jiulong, it dawned on me that
I was, quite possibly, holding in m y hand the only introduction of this wlique maple since its initial introduction in either 1929 or 1937.
Despite tllis species'
parthenocarpic tendencies a nd its reputation for being difficult, if not impossible,
to ge rminate, we managed to grow seve ral, seven of wluch survive in our collection
Leaf detail of Acer pentaphyllum
at Quarryhill Botanical Garden today. As far as we know, with the loss of the trees
a t Strybing Arboretum, ours are the only living trees of \vild origin of this species in
North Ame rica. W./e did distribute two of our seedlings to UC Berkeley Botanical Garden, but tl1ose did not survive. Four of our trees were
plan ted in partial shad e in May of 1996 and are now two to three meters tall with the widest at three meters. The other three were planted in
March of 2001 in full s un a nd have reached a meter. All seven are quite healtl1y, although tl1e leaders on the first fout have given up donlinance to a
side bra nch.
During a visit to the Muli area of southwestern Sichuan in the fall of 1992, I again was hopeful that I nlight find tills maple. Despite days of
searclling in areas near Rock's original discovety, we found no trees of Ai:er pentapl!]llum. In the spring of 2001, while traveling north from the Yalong River up the Jiulong River to Jiulong I was optimistic that I would complete m y quest. I knew that the road passed b y the area that we had
been told a bou t during my first visit to Sichuan. We were told to look for a certain footbridge across the Jiulong River and that the trees were a
short distance beyond a small settlement on the other side of the river. Despite stopping at bridges of various sizes and shapes, even at bridges
that were all or pa rtly destroyed, and asking local villagers, we could not find the elusive trees.
Finally, on another collecting trip in September of 2001, we a rrived in Jiulong confident that we would at las t see the Acer pentapf!J IIttm in the wild. I
was traveling with Tony Kirkham a nd Steve Ruddy from the Royal Bota nic Ga rdens, Kew, and Mark Flanagan from Windsor Great Park, along
witl1 Dr. Yin Kaipu who had pronlised to take us to the actual site. We were all very worn out and tired from several weeks of fieldwork collecting
seeds and herba rium specimens arow1d Gongga Sha n. Most recently we had been ca mping in the rain near tl1e Tibetan village of Liuba west of the
massive mountain and so we were very much looking forward to hot showers, a swnptuous dinner, and warm comfor table beds. Jiulong, meaning
nine dragons, is named in honor of nine surrounding peak s. The rather unkempt town is made up of one-third Yi people, one-third Tibeta ns and
one-tlurd Hans.
We a rrived in the late a fternoon a nd after a brief introduction with the local' ad ministra tors, a nd an invita tion for dinner, we headed for our hotel.
Our exhaustion quickly turned to frustration as we were told that not only was there no hot water, there was no water a t all, not even to flush a
toilet. r\pparently the wa ter main for the entire town was being repaired and tl1ere would be no running wa ter for three more days. At leas t we
had dinner with tl1e governor to look forward to. This turned out to be a large bowl with a horribly scrawny undercooked chicken with its head
against the rim as if taking a bath, along with a salty dish of very fatty pork a nd a nothe r bowl of s tringy yak with turnips, all of which were cooked
with copious amounts of garlic. I ate only garlic cloves and turnips washing them down with beer. It was the worst dinner of the entire journey.
The next monling, after a smprisingly good nigh t's sleep in a rather comforta ble bed, we headed south a lit tle before nine. About fif ty nlinutes
late r having traveled twen ty-four kilometers, we stopped a t a n ornately painted foo tbridge. On the other side of the river was a small settlement of
stone houses called Rala. We crossed the bridge and walked through cornfields jus t above the river. J\fter passing a large stone house, the path
beca me much s teeper with the slope at times almos t vertical. A little more than one hw1dred meters beyond the stone house, on our left, just a
few meters below tl1e pa th, stood a healthy A(er pentapi!J IIum. It was about ten meters high with a spread of a bout ten meters. The trilllk was almost a meter in diameter at the base and quickly divided into two main trunks, one about thirty centimeters and the other about forty-five centimeters in dia meter. The tree had obviously been cut several times, a ppa rently for fuel, giving it a dense shrubby appearanq:. There was a large quantity of seed, all on the soutl1 side of the tree. Looking a round, we saw what we thought were six more trees sca ttered on the steep slope above us.
\Y./e were told that there were less than twenty trees, but time did not allow us to inves tigate further. Dr. Yin then told us iliat this was the last
known stand of Acer pentap f!JIIum. As ilie significance of his remark sunk in, I looked around again at the few trees in the distance. We were standing a bou t SL'\.ty meters above the Jiulong River in a deep canyon of exceedingly steep mountains. Though not yet ten o'clock, it was almost 70 degrees Fahrenheit (20 Celsius) with a few low clouds hugging the mountain tops. The maples were growing with evergreen oaks, roses, a nd ashes on
a soutl1western exposure at an eleva tion of 2,580 meters. Although the villagers had been told by the government in 1988 to protect the trees,
there were no fences and no sign of regenera tion. Goats a nd sheep grazed freely nearby. It was hard to imagine iliese few ra re trees surviving
another twen ty yea rs.
\Vhen Joseph Rock found A(er pentaphyllum seventy-two years earlier, there were far fewer peo ple living in these rugged mountains. But, even then,
he noticed that they were rare. \Vhether there a re other small stands growing in isolated unexplored mountainsides in Sichuan is unknown. Wha t
is known is tl1at we are losing species rapidly, most before we even have a sligh t unders tanding of them. U nfortuna tely, these maples were growing
near the homes of subsistence fa rmers, themselves living on the edge, where a ny tlling burnable is an important resource. Thankfully the number
of maple enthusiasts is increasing a nd \vill hopefully insure the survival of Ac-er pentapl!]llum, a t least in cultiva tion. It is curious tha t ilie ornamental
pla nts that have made i t into our gardens, through our devotion to their beauty, have in ma ny cases secured ilieir long-term survival. For countless
other species, known and unknown, the future remains in question.
Acknowledgments
I JPiJlJ to thank Bian Tan, Elaine Sedlack, John Domzalski, Hoi!J Forbes, S( ot M edbury, Don Mahonry, Jak e Sigg, Maggie U];dJ, Randall Hitchin, Peter Raven, Mai
Arbegast, St"ott M(Mahan, Ted !Vpping, john Kipping, Fred Coe, Pete Lowry, Charles Erskine, and To'!Y Avent for helpful tYJtnments and anecdotes.