Trachycarpus oreophilus - The Thai Mountain Fan Palm
Restricted to a tiny area in N. Thailand, it's
turned out to be as difficult to collect good seeds as it is to
germinate them. May be a while before this one is available at your
local garden centre.
Martin
Gibbons & Tobias
W. Spanner
Chamaerops No.35/36, Summer-Autumn Special 1999
Pictures: Trachycarpus oreophilus, Doi Chiang Dao,
Thailand
When Dr. John Dransfield of Kew told us that there
was 'a Trachycarpus' growing in northern Thailand that 'needed investigating,'
it seemed a heaven-sent way to fill the four spare days at the end
of the trip to China we were planning to try to find Trachycarpus
nanus (Gibbons, M. & T. W. Spanner 1993. In Search of
Trachycarpus nanus. Principes 37:64-72.). John
told us that the palm had originally been 'discovered' in the 1920's
by A. G. F. Kerr, renowned British botanist (of Kerriodoxa fame)
and was well known to the Royal Thai Forestry Department, but that
it had been mistakenly classified as a Livistona. Its description,
herbarium specimens (though lacking fruit or seeds), and a black-&-white
photograph had languished in the herbarium at Kew until the 1970's
when John spotted the mistake. It was certainly a Trachycarpus,
and in the absence of seed material which might indicate which one,
it had been classified as T. martianus, which it certainly resembled.
This assumption was proven wrong when, in the mid-1980's, some fruits
were collected by the Royal Thai Forestry Department and were sent
to Kew for inspection. They were reniform (kidney-shaped) as opposed
to the T. martianus' oval-and-grooved, and a question mark has hung
over its true identity ever since. This puzzle could have been invented
for us, and we gladly took up the challenge to throw some more light
on the subject.
John kindly suggested the names of two botanists in
Bangkok who might be able to help us, and a visit to one of them,
Weerachai Nanakorn, on our arrival in Thailand led to us meeting
Rachun Pooma of the Royal Thai Forestry Department in Chiang Mai,
who knew of this palm and was as excited as we were by the prospect
of a trip to see it.
He was extremely helpful, meeting us at Chiang Mai
airport, accommodating us at his residence at the Huey Kaew Arboretum,
and taking us out that first evening for a wonderful Thai meal.
The following day, he arranged a 4-wheel drive jeep, complete with
driver, and to pick up a couple of guides en route. We set off at
10am, stopping on the way to get supplies for the two days we would
be away. We then drove out of Chiang Mai and after a couple of hours
turned into a side road, heading for the mountain range, where grew
our quarry.
The jeep was very powerful. Rachun sat in the front
with the driver, and we sat in the open back on a plank fixed to
serve as a seat. However, as we began to climb, the road became
so rough and bumpy that we were obliged to stand, from which position
we had an excellent view of the changing scenery and vegetation.
The temperature fell slowly as we went up, and coconut palms gave
way to huge Livistona speciosa (= L. jenkinsiana), wonderful and
noble trees, growing wild in the forest. This species also grows
in north Burma and possibly in south China, and, apart from some
minor differences in the fruit and inflorescence bracts, it is hardly
distinguishable from Livistona jenkinsiana from north-east India
and should perhaps be considered synonymous with it. There were
also hundreds of bamboos of all shapes and sizes arching across
the road, sometimes forming a tunnel. Other interesting palms we
saw were the trunkless Wallichia caryotoides, and various rattans,
all growing in deep shade.
The road became atrocious with deep muddy ruts and
areas where the road had been washed away. The 4-wheel drive was
quite indispensable as the road was steep as well as muddy. Sometimes
the rear of the vehicle seemed in danger of overtaking the front,
and sometimes we slipped dangerously close to the edge of the road
and a sheer drop.
We continued in this way for some two hours, upward
and ever upward. From time to time we saw our destination through
the trees: Doi Chiang Dao - a mysterious and extremely steep, relict
limestone mountain, separated by time and distance from the vegetation
of the surrounding countryside. After this difficult journey we
arrived at "base camp," an outpost of the Forestry Department,
where lived and worked the forest rangers with wives and children,
some 10 to 15 people in all. It was now about 2pm, leaving us without
enough time for the climb up, so we would stay the night here and
set off in the morning.
There was not much to do, though we did walk for half
an hour to a vantage point to have a closer look at 'our' mountain.
My goodness it looked awfully steep! With binoculars we could make
out hundreds of palm trees silhouetted on its crest. They looked
far too exotic to be humble Trachycarpus, but that's indeed what
they were. On the way we came across some very large Cycas pectinata.
Some of them must have been hundreds of years old, and were forked
and branched. Back at the camp we had some food and the time passed
quickly enough. At about 8pm we retired and slept surprisingly well
on the hard and thin mattresses.
We rose at 7am. The weather was quite cool as the
sun was only just rising. There were 6 of us in the party: Rachun,
his assistant, two forest ranger guides who knew the way up to the
top, and the two of us. We set off taking the same path as yesterday.
At first the going was quite easy with the path clearly defined,
but as we ascended it became less clear, more muddy, and with the
vegetation closing in. We climbed up the muddy path, slipping and
sliding and hanging on to the plants for support, with tantalising
glimpses of our goal appearing from time to time. Up and up we went,
around the side of the mountain. It was very steep in parts and
very heavy going. After a couple of hours' tough climb, we departed
from what little path there was to make a direct assault. At this
point the going became even more difficult and we were drenched
by the wet vegetation.
What appeared from a distance to be short grass turned
out to be 6 feet high. This grass was studded with huge limestone
boulders the size of cars, keeping us faced with the dilemma of
going around or over them. The palms got closer and closer but they
were absolutely on the ridge crest and demanded a high price for
access. We aimed for one particular palm whose leaves we could see
arising from the far side, and slowly inched our way towards it.
The last few metres were over the bare rock itself, where sharp
ridges had been formed by erosion. We slowly made our way towards
the crest and this tree, but as we reached the edge and looked over,
expecting to see a gentle slope on the other face, we saw that the
far side was absolutely sheer: a dropped stone would have been in
free fall for several hundred feet.
The palm tree that we had chosen was growing from
the sheer face of the far side and therefore quite inaccessible.
We worked our way with great difficulty along the ridge in an effort
to reach some others, and there were many to choose from, but each
required an individual expedition of perhaps 20 minutes, and a slow
climb up, over, or around the huge limestone boulders to reach it.
Not all these rocks were secure, some moved, some had eroded into
huge stones balanced on others. A push would have sent them crashing
down.
Well, what of the trees themselves? It must be said
that they were quite stunning. They were all growing in the most
inaccessible locations on the cliffs and ridges of weathered limestone.
We assumed that all the more reachable trees had been cut down for
some purpose, and this was later confirmed by one of the guides.
The first striking thing about them was that they
had bare trunks, some up to 30 feet tall and rather slender, closely
ringed with leaf scars that were faintly visible under a cover of
moss and lichens. All the leaves were stiff and erect, forming a
dense, upright but rather flat crown with only a few dead leaves
hanging below the horizontal. The leafblade, petiole, and the short,
fibrous leafsheath apparently decompose soon after the leaf has
died, leaving only the thick leafbases persisting on the trunk for
50cm below the crown before they, too, eventually fall.
The atmosphere was very moist, with clouds regularly
obscuring the view: an incredible sight with the mountain, the palms,
and sometimes the hot, steaming lowlands far below, appearing and
disappearing in the mist. Like most of south-east Asia, northern
Thailand is influenced by the monsoon and receives copious rainfall
in the summer while experiencing a moderate dry season during the
winter. We made our way down from this terrible crest to a relatively
flat area where we had lunch. We decided to explore another crest
- again heavy going - and as we reached the palms we saw that one
of them was in full fruit. The tree had five infructescenses which
did not hang down in the manner of T. fortunei but projected out
stiffly at only slightly below the horizontal.
It was growing, predictably, on the edge of a precipice
that we hardly dared look over. With some difficulty we collected
samples of leaves and leaf sheaths as well as several hundred green
but ripe kidney-shaped seeds. The fibrous leaf sheaths are quite
notable in that they are short with a rather furry and appendage-less
upper margin, and of a fine, rather soft texture, rapidly breaking
down. The leaf blade was split to a very regular depth and was carried
on a robust petiole, separated from the blade by a long and prominent
hastula.
Seeing these characteristics, our earlier suspicions
were certainly confirmed: what we were looking at was a new, undescribed
species, clearly distinct and easily separated from all other members
of the genus. With our collections adding to our load, we began
the dreaded return trip, made considerably worse by heavy rain.
After an exhausting journey slipping and sliding down
the muddy path, we were on the original track and heading for home,
triumphantly bearing the spoils of our expedition. When we finally
reached the base camp, we had a welcome cup of coffee and climbed
aboard the jeep for the two hour drive down the mountain. What had
been mud on the way up had, with the rain, become a quagmire, sometimes
axle-deep. The going was awful; there was no shelter on the back
of the truck and we were again soaked through. Down and down we
went, past bamboo and Livistona, miraculously making it safely back
to Chiang Mai with no major problems.
Two years later, in 1994, we returned to Doi Chiang
Dao and its Trachycarpus to explore a few more remote and less accessible
ridges and to collect additional material. Though the climb both
up and down was exhausting and dangerous, our excitement and pleasure
at being able to describe a new species of Trachycarpus made the
effort and risk well worth while.
Trachycarpus oreophilus Gibbons & Spanner
Solitary, very lightly armed, dioecious palm to abt.
9m tall; trunk slender, erect, bare, brown, conspicuously ringed,
10-16cm in diam., in young plants occasionally clothed in persistent,
fibrous leafsheaths. Leaves abt 20, forming a dense upright, rather
flat crown; marcescent leaves few, leafblade, petiole and leafsheath
soon deciduous, the thick, almost bulbous leafbases persistent at
first, covering the trunk for abt. 50cm below the crown, eventually
deciduous; leafsheath fibrous, abt. 30cm long, brown, fine, soft,
rapidly disintegrating, thinly tomentose below, separated into short
single threads towards the apex, not forming an appendage; petiole
abt. 50cm long, stiff, robust, 2cm wide near the middle, flattish
above, depressedly triangular to rounded below, margins minutely
toothed and thinly tomentose, base thick and robust; adaxial hastula
prominent, to 3cm long, triangular, acute; leafblade palmate, 3/4
to nearly 4/4 orbicular, abt. 70cm long from the hastula and abt.
100cm wide, leathery, green above, glaucous below, parted to a nearly
even depth for more than 1/2 its length into abt. 60 stiff, deeply
folded, linear segments, tapering towards the apex from their broadest
point; central segments abt. 70cm long, lateral segments gradually
shorter to 40cm, apex acute-notched, shortly bifid for a few cm.
Inflorescences about 4, solitary, interfoliar, 90-100cm long; staminate
inflorescence erect, peduncle short; prophyll 2-keeled, 25cm long;
peduncular and rachis bracts five, 15 to 25cm long, base tubular,
inflated distally, apex acute; rachillae short; flowers globose,
very small; sepals very small, ovate, joined at the base for 1/4
to 1/5 of their length; petals rounded with a blunt tip, 2,5 times
as long as the sepals; stamens 6; filaments ventricose; anthers
broadly ovate-sagittate with nearly disjoint cells, not apiculate;
pistillodes (2-) 3, half as long as the stamens; pistillate inflorescence
stiff, slightly arching or nearly horizontal in fruit, densely branched
to 3 orders; peduncle abt. 50cm long oval in cross section, 3,5
x 2cm; prophyll 2-keeled, apex acute; peduncular bracts three, 35cm
long, long and tubular; rachis bracts two, the basal one 25cm long,
similar to peduncular bracts, the distal one small and much reduced;
rachillae 3-10cm long, greenish (in fruit); flowers not seen. Fruit
on short stalks, reniform, wider than long, epicarp thin, green,
not seen when fully mature; mesocarp thin, fibrous; seed reniform,
wider than long, 6mm long, 11 mm wide; endocarp very thin, with
a crustaceous sand-like layer of small, irregular scales; endosperm
homogenous. Germination remote-tubular, eophyll simple, plicate,
papery, 1 cm wide. Seedling leaves narrow, erect and very finely
divided.
Distribution:
NW-Thailand: Doi Chiang Dao, a large, isolated limestone mountain
abt. 70km N of Chiang Mai, forming large colonies on steep, rocky
hillsides and exposed cliffs among lichen- and moss-covered shrubs
and stunted trees on the mountain's several peaks, between 1700
and 2150m. Recently more colonies have been found on nearby peaks
and might extend into N-Burma.
Conservation Status:
The Doi Chiang Dao population consists of a few thousand trees and
is protected in a forestry reserve. It appears to be in a good state,
though all the more accessible sites have long since been cleared
of palms by tribespeople, leaving no seedlings and few young plants
present.
However, the vast majority of the palms grow in very steep, practically
inaccessible sites and as pressure on these stands by man or beast
is negligible, their future seems secure. We would categorize it
as 'rare.
Trachycarpus oreophilus has only recently been introduced
into cultivation. There are no mature palms of this species outside
its native habitat. Plants seem to grow very slowly.
The specific epithet (Lat. oreophilus, cloud loving)
relates to the fact that this palm and its habitat are often totally
obscured by clouds.
Note: As there is no recent taxonomic treatment
of the genus Trachycarpus (but see Beccari, O. 1931. Asiatic
Palms: Coryphae. Ann. Roy. Bot. Gard., Calcutta 13:272-256.
and Kimnach, M. 1977. The species of Trachycarpus. Principes
21:155-160.), relationships of T. oreophilus will be dealt with
in a conspectus of the whole genus, which will appear in a later
publication.
We would like to take this opportunity to thank Dr.
John Dransfield of the Royal Botanic Gardens, Kew, for bringing
this species to our attention, for his continued support and his
help with the manuscript, and Weerachai Nanakorn and the Royal Thai
Forestry Department - especially Rachun Pooma - for their indispensable
help. Additionally, our thanks are due to Anders Barfod, University
of Århus, Denmark, who supplied a herbarium sheet much needed
to complete our description.
This article was first published in 1997 in Principes
Vol. 41, No. 4 and has been edited to fit the format of Chamaerops.
|
|
[an error occurred while processing the directive] |