Notes on gutta-percha and caoutchouc-yielding trees. {With a post script H.J. Murton
F.W. Burbidge, a botanist recently travelling in North-West Borneo, presented these notes to the Straits Branch of the Royal Asiatic Society in June 1879, with supplementary remarks by W.H. Treacher, Colonial Secretary of Labuan, and a postscript by H.J. Murton. The article addresses the persistent botanical confusion surrounding the identity of gutta-percha and rubber-yielding plants in Borneo, arguing that the commercial varieties had been misidentified—most notably as Urceola Elastica—and that proper taxonomic clarification was essential to securing the long-term supply of these commercially vital products.
Summary
Burbidge’s central contribution is a field-based enumeration of the gutta-percha and caoutchouc-yielding plants of North-West Borneo, drawn from his observations along the Lawas and Limbang rivers. He distinguishes five species of Isonandra (Sapotaceae) as the sources of hard, inelastic gutta, each identifiable to local Kadayan and Murut collectors by trunk dimensions, leaf morphology, and yield, yet all sold indiscriminately under the common trade name “Gniato Merah.” For the elastic rubber (caoutchouc), he describes three kinds of woody climbers distinguished by stem corrugation, bark colour, and fruit shape—pear-shaped, round, or small and round—whose milky exudation is coagulated with Nipah salt and sold as black balls of roughly half a catty each.
Treacher’s remarks, appended as Colonial Secretary of Labuan, provide the commercial and administrative framing: a table ranking the Isonandra species by value per picul at Labuan, a correction of Burbidge’s nomenclature (preferring “Manungans” over “Serapits” as the primary commercial rubber), and the observation that Serapit milk is used only to adulterate Manungan produce because it will not harden sufficiently on its own. He also notes that the term “Gutta Merah” is a misnomer—the red colour being an artificial product of bark filings mixed into the natural gutta in a ratio of one-third to two-thirds, a practice unknown to Chinese buyers who preferred the adulterated article.
Murton’s postscript, drawing on identifications made at Kew by Professors Dyer and Oliver, resolves several of the taxonomic questions raised. The Bornean rubber climbers are confirmed as Willughbeia (not Urceola), with one specimen identified as Chilocarpus and the Perak “Gutta Singgarip” equated with Wallich’s Willughbeia martabanica. Murton further reports that hundreds of young plants of at least five rubber-producing climbers had been established in the Singapore Botanic Garden, and he raises the prospect that Bornean Ficus and Artocarpus species might yield marketable gutta, while noting that the inferior quality of Malayan rubber compared to South American grades was attributable to the “slovenly” preparation methods of Malay collectors rather than to the raw material itself.
Key Findings
- Isonandra Gutta (Gutta Merah): trunks 100–150 ft tall, 1–3 ft diameter; a single large trunk yields up to one picul of prepared gutta (p. 53).
- Gutta Bulu: trunks reaching 3–4 ft diameter, yielding 20–30 catties of gutta per tree—the highest-yielding species described (p. 54).
- Commercial values at Labuan: Isonandra Elong $35–40 per picul; I. Maresah $28–30; mixed inferior species $5–20; rubber (caoutchouc) $20–30 per picul (p. 57).
- “Gutta Merah” (red gutta) is an adulterated product: one-third bark filings mixed with two-thirds natural gutta, a practice unknown to Chinese traders who preferred the red variety (p. 57).
- Professor Dyer at Kew confirmed that Bornean rubber plants do not belong to Urceola Elastica; Professor Oliver identified a Serapit specimen as Chilocarpus, and the Perak “Gutta Singgarip” as Willughbeia martabanica (pp. 52, 60).
- Murton’s unprocessed rubber sample, submitted to London judges, was valued at 1s. 3d. per lb., exceeding the 1s. per lb. paid for the best commercially prepared brands, demonstrating that preparation method—not raw quality—determined market value (p. 61).
Conclusion
The article’s definitive takeaway is that the commercial confusion surrounding Bornean gutta and rubber was rooted in taxonomic error and the indiscriminate mixing of distinct species’ produce, and that systematic botanical identification—now underway through the Kew and Singapore Botanic Gardens—was the necessary precondition for both scientific understanding and the economic perpetuation of the supply.
Context
- The article draws on field observations from the Lawas, Limbang, and other rivers of North-West Borneo (present-day Sabah), with botanical identifications made at the Royal Gardens, Kew, and the Singapore Botanic Garden.
- Treacher’s remarks reflect the colonial administrative interest in Labuan’s trade in forest products, while Murton’s postscript (dated 29 July, likely 1879) represents the ongoing Kew-based taxonomic programme that would eventually resolve the nomenclature of Malayan gutta and rubber species.