The Trees Yielding Benzoin.
By E. M. HOLMES, F.L.S.
The benzoin which enters into English commerce includes four varieties named respectively Sumatra, Palembang, Penang and Siam benzoin. These exhibit certain characteristic appearances by which they are easily recognized, and three of them, namely, Sumatra, Penang and Siam benzoin, are probably derived from three distinct plants. The botanical source of Sumatra benzoin was determined by Dryander, and an account and figure of the plant were published by him in the Philosophical Transactions, for the year 1787, lxxvii., p. 303, but the trees which yield the other varieties have as yet never been identified with certainty. The Penang benzoin is similar in appearance to the Sumatra kind, but it has an odor which is quite distinct and resembles that of storax. It is in all probability not produced by Styrax benzoin; but we have as yet no accurate information concerning the botanical source of Penang benzoin. The authors of "Pharmacographia" point out that it may perhaps be the produce of Styrax subdenticulata, Miq., since this tree, which occurs in West Sumatra, has the same name, "Kajoe Kéminjan," as S. benzoin, and Miquel remarks of it an etiam benzoiferum? That these two species should receive the same native name in Sumatra is not surprising since the leaves are very similar in shape and appearance and the fruit of S. subdenticulata apparently only differs from that of S. benzoin in being obovate instead of globular and depressed.
Palembang benzoin resembles the Sumatra sort in odor and differs from it chiefly in its much greater transparency and in yielding, as I am informed, a larger percentage of benzoic acid. It frequently contains moisture and if recently imported specimens are placed in a bottle they soon become mouldy. Concerning the tree which yields Siam benzoin, nothing definite has hitherto been ascertained, although as long ago as 1859, Mr. D. Hanbury wrote to Sir R. H. Schomburgh, asking him to investigate the origin of the resin, and to find out whether the tree which yielded it was really Styrax benzoin. Nor have subsequent inquiries been more successful. The only account extant of the mode of collection of Siam benzoin is that given by Sir R. H. Schomburgh, who was British Consul for some years at Bangkok. He, however, never visited the region producing benzoin and could therefore only give information at second-hand. He represents that the bark is gashed all over and that the resin which exudes collects and hardens between it and the wood, the former of which is then stripped off. The authors of "Pharmacographia," remark that it is evident that all Siam benzoin is not thus obtained. Schomburgh adds that the resin is much injured and broken during its conveyance in small baskets on bullocks' heads to the navigable parts of the Menam river, whence it is brought down to Bangkok.
The state of our knowledge of Siam benzoin being thus imperfect, it occurred to me to write to Mr. R. Jamie, of Singapore, to ask him for information on the subject. This gentleman takes great interest in all that relates to pharmacy, and has, I believe, been a liberal contributor to the Museum of the North British Branch. A few weeks ago I received from him a box of specimens for the Museum of the Pharmaceutical Society, containing amongst other interesting and valuable donations some sections of the trunk of the Siam benzoin tree, and herbarium specimens of the leaves, but unfortunately neither flowers nor fruit; also specimens of the Sumatra benzoin tree with leaves, flowers and fruit. In addition to these specimens be has contributed some interesting information, which I have taken this early opportunity of laying before you. With regard to the Siam benzoin plants Mr. Jamie writes:
"My friend, Captain Hicks, of Bangkok, kindly procured them after very great difficulty from his friend living in the district where the gum benzoin trees are found, and he writes as follows:— 'According to your request I had fifteen gum benjamin plants brought over from Suang Rabang, one of the northern Laos states tributary to the King of Siam, but after a deal of shifting and removing baggage on bullocks, twelve of them withered up; however, I have succeeded in getting three of them brought to Chung-mai; these I now send you. The one in the flower pot seems to be thriving remarkably well, but the other two in bamboo joints I have my doubts about. I also send you some sections of wood with the bark attached, and here and there you will find the gum sticking on the wounds and incisions made by the natives. The flowers, I am sorry to say, I could not get, as the trees have already flowered. From reliable information the tree is indigenous, in all the northern Laos states, but grows luxuriantly in Suang Rabang and all along the belt of mountains in this province.'
"In the months of April and May the leaves begin to wither and fall off, and the natives then make incisions in the bark, and after a short time a lot of milky substance exudes and soon hardens; the gum then dries on the incisions and falls to the ground, which is swept daily and watched so that no earthy matter gets mixed up with it.
"The tree attains from 3 to 6 feet in circumference, and has a long trunk throwing out branches on the top; after six years' growth it can be bled. The flowers are attached to the small branches close to the leaves and begin to flower in June. The tree throws out shoots from the roots, and can be propagated by cuttings. The natives also say that after the flowers fall off, in a short time a lot of young plants spring up. (This evidently means that the seeds quickly germinate as is the case with those of the Sumatra benzoin tree.) The gum is a considerable article of traffic, in fact a monopoly, fetching a good price in the Bangkok market. It is used generally for fumigating sick rooms and making scented water. Large quantities generally find their way to Bangkok, being brought overland on oxen to Sawaryaloke, Pitchal, and other Siamese provinces, and are exported to Europe by several mercantile firms."
Of the three young plants above mentioned, one was given by Mr. Jamie to the Curator of the Singapore Botanical Gardens to forward to Kew, a second was planted in Mr. Jamie's own garden, and the third died.
The twig which I now exhibit was taken by Mr. Jamie from the young plant in his garden. The specimen sent to Kew is still living and seemed to be in a healthy state when I saw it a fortnight since. Judging from the appearance of the plant at Kew and from the leaves sent by Mr. Jamie the Siamese benzoin tree is probably a distinct species, although nearly allied to S. benzoin, Dry. The leaves are rather thinner, the lateral veins are fewer in number and the veinlets more prominent beneath, but it is necessary to wait until flowers and fruit are obtained before the exact species to which it belongs can be ascertained. Mr. Jamie has now the two growing together in his garden, and remarks in his letter, "Judging from what I have seen of the two kinds growing together, they are different."
I have compared the specimens of the Styrax benzoin tree from Mr. Jamie's garden, with Dryander's original specimen in the British Museum, and they correspond exactly.
Concerning this tree Mr. Jamie writes:—"The Singapore grown tree is thought to be from Palembang, (If so, then, it supports my supposition that Palembang and Sumatra benzoin are produced by the same tree.) it is about 30 feet in height, and the branches are all at the top. The circumference of the trunk is from 14 to 16 inches. It flowers in March and the fruit does not take long to mature, then it falls off, producing seedlings in abundance at the foot of the tree. How old this tree may be is rather difficult to determine, but it must be over thirty years at the least."
The tolerable certainty that in a short time flowers and fruit of the Siam benzoin tree will be obtainable, and that the source of the drug can then be definitely set at rest, must be my excuse for bringing incomplete information before you. I need none for bringing the admirable specimens presented by Mr. Jamie under your notice.