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

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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.“

 

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