Gaultheria (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Gaultheria leucocarpa: 1, flowering and fruiting branch; 2, flower; 3, longitudinal section through flower; 4, stamen; 5, cross-section through ovary.

Gaultheria L.

Protologue: Sp. pl.: 395 (1753); Gen. pl., ed. 5: 187 (1754).

Family: Ericaceae

Chromosome number: x= 11, 12, 13; G. leucocarpa: 2n= 44

Major species and synonyms

• Gaultheria leucocarpa Blume, Bijdr.: 856 (1826), synonyms: G. crenulata Kurz (1873) (for var. leucocarpa f. cumingiana), G. cumingiana Vidal (1885) (for var. leucocarpa f. cumingiana), Brossaea leucocarpa (Blume) O. Kuntze (1891).

• Gaultheria punctata Blume, Bijdr.: 856 (1826), synonyms: G. fragrantissima auct., non Wallich (1820), Brossaea fragrantissima (auct.) O. Kuntze (1891), G. fragrantissima Wallich var. punctata (Blume) J.J. Smith (1914).

Vernacular names

General:

• wintergreen (En).
• Petit thé des pois (Fr)
• Vietnam: châu thụ.

G. leucocarpa :

• Indonesia: gondopuro (Javanese), kering, cantigi bodas (Sundanese)
• Philippines: logaway (Bagóbo)
• Thailand: chamayomdoi (Chiang Mai).

G. punctata :

• Indonesia: gondopura (Javanese), gandarasa, cantigi seungit (Sundanese).

Origin and geographic distribution

Gaultheria occurs in the Americas, Asia and Australia. The largest number of species is found in Central and South America (about 85), followed by eastern Asia (about 30 species). There are 24 species in Malesia. G. leucocarpa is commonly found from Burma (Myanmar) and southern and south-western China through Malaysia, Sumatra, Java, to the Philippines. G. punctata is less common and its distribution is restricted to Indonesia (Sumatra, Java and Bali).

Uses

The leaves and flowers of several Gaultheria species yield wintergreen oil, which has an intensely sweet-aromatic, medicinal fragrance and flavour with a creamy-fruity top note and a sweet-woody dry-out. The oil was formerly used extensively to flavour drinks, in perfumes and in medicine. Its best known use is in root beers and cola drinks, while herbal tea is made from fermented leaves. Other products flavoured with wintergreen oil are candies, chewing gum and toothpaste. Only minute quantities (0.2-0.5 mg per 100 g) should be used, as the taste is prominent. In perfumery, traces of wintergreen oil may add natural notes to e.g. ylang-ylang, tuberose, narcissus, lily and gardenia. It is now rarely used in perfumery, however, because a cheap synthetic form of its main chemical component, methyl salicylate, is available. Isolated natural methyl salicylate is still used in the flavour industry.

Gaultheria is used medicinally against rheumatism, neuralgia, sciata and cancer and also for its carminative and anthelminthic properties. It is a mild antiseptic in mouth care products, e.g. against toothache and sore throat. It is applied in ointments and liniments for its anti-irritant properties. The oil is also a component of insecticidal and insect repellant preparations.

Wintergreen oil from G. punctata is used in Indonesia to enhance the smell of finely cut leaves of Pandanus amaryllifolius Roxb. (rampeh) and to perfume clothes. Leaf paste is applied externally to ease chest complaints, while in concoctions it is occasionally used as a prophylactic before and after childbirth. The oil is applied in hair oils to control loss of hair. The leaves of G. punctata are occasionally chewed together with those of Piper betle L. and are used in herbal teas. G. leucocarpa is used similarly, but yields much less wintergreen oil. The leaves are used in traditional medicine to treat coughing, tuberculosis, fever and pain. The seeds of both species are used in handicrafts.

Several Gaultheria species are grown as ornamentals.

Production and international trade

In South-East Asia, Gaultheria is only processed for essential oil on a local scale, for flavouring and medicinal purposes. The well-established production of wintergreen oil from G. procumbens L. in North America and especially the production of synthetic methyl salicylate make large-scale steam distillation in South-East Asia uneconomical.

Properties

The main constituent of wintergreen oil is methyl salicylate. Oil from G. leucocarpa from Malaysia contains 96% methyl salicylate. The content of methyl salicylate in some other species is even higher. Most plant parts contain methyl salicylate or its precursors. Fresh leaves and flowers have hardly any odour, but the characteristic odour becomes apparent when they are crushed and stored for a short time. Methyl salicylate is then formed by hydrolysis of glycosides. The oil contains minute quantities of alcohols and ketones. See also: Composition of essential-oil samples.

In the United States wintergreen oil is "generally recognized as safe" (GRAS No 3113). It is included in the Food Chemical Codex. The maximum use level in food products is 0.04% (in candies). When taken in large amounts methyl salicylate is toxic and causes problems similar to those caused by high doses of aspirin. The acute oral lethal dose (LD50) is about 1 g/kg body weight in the rat. It is a severe eye irritant, but reports on its irritating effect on the human skin are contradictory.

Adulterations and substitutes

For application in perfumery methyl salicylate is almost exclusively produced synthetically. Natural products are sometimes adulterated with the synthetic product for this purpose. Only the natural product is used for flavouring, however.

Description

• Evergreen shrubs or half-shrubs, rarely epiphytic, erect or rarely procumbent, prostrate, creeping or climbing.
• Leaves arranged spirally or very rarely opposite, mostly serrate.
• Inflorescence a terminal or axillary raceme or a terminal panicle, sometimes reduced to a few-flowered fascicle or a solitary flower.
• Flowers rather small; pedicel subtended by a large basal bract and 2(-3) higher inserted, mostly small bracteoles; calyx 5-lobed, lobes imbricate, persistent, becoming enlarged, swollen and succulent in fruit, mostly dark purple or almost black; corolla campanulate or urceolate, shortly 5-lobed, lobes imbricate, spreading or recurved; stamens (8-)10, included, attached around the disk to the base of the corolla; filaments mostly dilated at or above the base; anthers dorsifixed, introrse, with 2 apical teeth; disk about 10-lobed, glabrous; ovary superior or semi-inferior, 5-ribbed, 5-locular; style simple, columnar; stigma small, obtuse.
• Fruit a thin to thick walled, 5-celled capsule, subglobose, enclosed in the fleshy calyx, loculicidally dehiscent from the apex into 5 valves, many-seeded.
• Seed minute, subglobose to angled-depressed; testa thin, reticulate.
• Seedling with epigeal germination.

G. leucocarpa.

• Slender shrub, 0.25-2(-3) m tall, climbing or somewhat decumbent. Branches flexuous, often pendulous; branchlets reddish or purplish.
• Leaves arranged spirally; petiole 3-9 mm long, purplish; blade ovate to lanceolate-ovate, 3.5-14 cm × 2-6.5 cm, base mostly subcordate, margin regularly, obtusely crenate-serrate with glandular, orange teeth, apex long acuminate to subcaudate, with a small terminal gland, firmly coriaceous, dull dark green above, paler beneath, glabrous or pubescent beneath.
• Inflorescence a simple, axillary, lax raceme, up to 10 cm long, many-flowered, glabrous or densely pubescent; pedicel recurved, 3-10 mm long; bracts and bracteoles ovate-lanceolate, ciliate; calyx about 2.5 mm long, deeply 5-partite, glabrous on both sides or puberulous inside, lobes ciliate and pale green or red; corolla campanulate, 3-4 mm long, usually glabrous, whitish.
• Fruit 6-9 mm in diameter, white, rose-tinged or red to black-purple.
• Seed triangular-obovoid, 0.5 mm long, brown.

G. punctata.

• Treelet or large shrub, (0.25-)2-3(-5) m tall, erect or decumbent-scandent. Branchlets stout, sharply trigonous or winged by the decurrent petioles.
• Leaves alternate; petiole 1-8 mm long, flattened, grooved above, red; blade elliptical-oblong, (2-)4.5-8.5(-10) cm × 0.8-3(-4) cm, base cuneate, often decurrent into the petiole, margin regularly, coarsely glandular-serrate, teeth rather blunt, apex gradually acuminate, obtuse by a terminal gland, subcoriaceous to coriaceous, glossy dark green and glabrous above, dull greenish-whitish and glandular-punctate beneath.
• Inflorescence an axillary panicle composed of many, erect, single racemes, (5-)7-10(-12.5) cm long; rachis trigonous, greenish; pedicel 2-9 mm long, white or pink; bract ovate-acuminate; bracteoles inserted immediately below the calyx, opposite, ovate-acute, 1.5 mm long; calyx 3-3.5 mm long, tube white, lobes ovate-acute, reddish, ciliate; corolla subovate-urceolate, 5-7 mm × 4-5 mm, lobes broadly triangular, recurved, white to pinkish-white, glabrous.
• Fruit 8-10 mm in diameter, dull red to dark red or blackish-purple. Seed obliquely obovoid-triangular, about 0.5 mm long.

Growth and development

In South-East Asia, G. leucocarpa and G. punctata flower throughout the year and self-pollination and self-fertilization seem to be the rule. Some flowers are protandrous with the stamens ripening on the first day and the stigma attaining maturity on the next day, but insect pollinators have seldom been observed. Practically all flowers set fruit. Flowering alternates more or less with fruiting. Plants that are fruiting abundantly generally bear few flowers at the same time.

Other botanical information

At present Gaultheria comprises about 135(-150) species, including species formerly described as Pernettya Gaud. The number of species for South-East Asia may increase considerably as a result of new discoveries in the partially explored mountainous regions of Borneo and New Guinea which are rich in Ericaceae.

The very widely distributed G. leucocarpa is rather variable and 3 botanical varieties have been distinguished in South-East Asia based on differences in fruit colour and hairiness (in China there are several more):

• var. hirta Valeton ex J.J. Smith: leaves, inflorescence and corolla pubescent; fruit unknown; only once collected in Sumatra.

• var. leucocarpa : leaves and corolla glabrous, ovary densely pubescent; distributed as the species. It is subdivided into 4 formas which geographically do not overlap: forma cumingiana (Vidal) Sleumer: fruit deep red to black-purple, inflorescence glabrous, occurring in Burma (Myanmar), Thailand, Indo-China, China, Taiwan, Peninsular Malaysia, Sumatra, Java and the Philippines; forma leucocarpa : fruit white or rose-tinged, inflorescence glabrous, occurring in Sumatra and Java; forma melanocarpa J.J. Smith ex Amshoff: fruit black-purple, inflorescence densely pubescent, occurring in Peninsular Malaysia, Sumatra and Java; and forma scandens Hochr.: fruit white or rose-tinged, inflorescence densely pubescent, occurring in Java and Sumatra.

• var. psilocarpa (H. Copel.) Sleumer (syn. G. psilocarpa H. Copel.): all parts glabrous; fruit dark red to black-purple; only known from the Philippines.

G. punctata has occasionally been regarded as belonging to G. fragrantissima Wallich. The latter, however, has very short, recurved inflorescences and much smaller flowers and is restricted to the Eastern Himalayas and the Khasia Hills.

Although no definite Gaultheria hybrids have been described from Asia, it is possible that G. intermedia J.J. Smith (collected from an unknown mountain in Java or Sumatra) is a hybrid between G. leucocarpa and G. punctata. Gaultheria hybrids are more common in New Zealand and South America.

The best known species yielding wintergreen oil is G. procumbens (Indian wintergreen), occurring naturally in the north-western United States and the adjacent part of Canada; it is also widely grown as an ornamental. G. malayana Airy Shaw from Peninsular Malaysia and G. nummularioides D. Don, occurring from the Himalayas to Burma (Myanmar), and in Indonesia (Sumatra, Java, Bali) are occasionally used for their wintergreen oil. Several other Malesian Gaultheria spp. also have a strong methyl salicylate odour but there are no indications of their use.

Ecology

Gaultheria species are mostly found in the lowest stratum of montane forest or as open country montane shrubs. G. leucocarpa occurs in montane forest and in open, exposed places among brushwood or shrubs at 1300-3300 m altitude. It is fairly common on the margins of craters, steep slopes, on stony, volcanic or sometimes peaty and generally poor soils. It is mostly terrestrial, but occasionally found growing as an epiphyte. G. punctata is locally common at higher elevations, mostly in open country on rocky, stony or volcanic soils. In Sumatra it occurs at 1000-3700 m altitude, in Java up to 3100 m.

Agronomy

In South-East Asia, Gaultheria material is mainly collected from the wild. The fruits, which are sweet with a slightly bitter after-taste, are eaten by birds and rodents, which are believed to be involved in seed dispersal.

Handling after harvest

The essential oil from Gaultheria is derived by steam distillation of the leaves. Prior to distillation the leaves are steeped in warm water to promote the enzymatic hydrolysis of glycosides to form methyl salicylate.

Genetic resources and breeding

No germplasm collections or breeding programmes of South-East Asian Gaultheria species are known to exist.

Prospects

Since wintergreen oil contains only one major component, and as additional components do not make an important contribution to the quality of the oil, it is unlikely that South-East Asian Gaultheria will again become an important source of methyl salicylate. The American G. procumbens can satisfy the demand for natural wintergreen oil.

Literature

• Arctander, S., 1960. Perfume and flavor materials of natural origin. S. Arctander, Elizabeth, N.J., United States. pp. 658-659.
• Hsu, Ting-zhi, 1981. Preliminary classification of Chinese Gaultheria. Acta Botanica Yunnanica 3: 417-434.
• Ibrahim, J., Abu Said, A., Abdul Rashih, A., Nor Azah, M.A., Mohd. Zaki & Azizol A.K., 1995. Essential oils of selected Malaysian plants and their potential uses. In: Norhara, H., Bacon, P.S. & Khoo, K.C. (Editors): Proceedings of the third Conference on Forestry and Forest Products Research. Forest Research Institute of Malaysia, Kuala Lumpur, Malaysia. pp. 97-103.
• Middleton, D.J., 1991. Ecology, reproductive biology and hybridization in Gaultheria L. Edinburgh Journal of Botany 48: 81-89.
• Middleton, D.J., 1992. A chemotaxonomic survey of flavonoids and simple phenols in the leaves of Gaultheria L. and related genera (Ericaceae). Botanical Journal of the Linnean Society 110: 313-324.
• Nor Azah, M.A., Abdul Rashih A., Ibrahim J., Abu Said A. & Noorsiha A., 1996. Metil salisilat daripada genus Gaultheria Linn. [Methyl salicylate from the genus Gaultheria Linn.]. In: Azizol, A.K., Khozirah, S., Ibrahim, J., Jamaluddin, I. & Nik Musa'adah, M. (Editors): Prosiding Konvensyen Kebangsaan Tumbuhan Ubatan [Proceedings of the National Cenvention on Medicinal Plants]. Forest Research Institute Malaysia, Kuala Lumpur, Malaysia. pp. 175-179.
• Perry, L.M., 1980. Medicinal plants of South-East Asia: Attributed properties and uses. MIT Press, Cambridge, United States. p. 133.
• Sleumer, H., 1966. Ericaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana, Series 1. Vol. 6. Wolters-Noordhoff Publishing, Groningen, the Netherlands. pp. 677-696.

Composition of essential-oil of Wintergreen oil (Gaultheria procumbens)

• 90.0% methyl salicylate
• 5.0% safrole
• 2.0% linalool
• 1.0% 1,8-cineole
• 0.5% α-pinene
• 0.5% β-pinene
• 0.5% camphor
• 0.2% para-cymene
• 0.2% eugenol
• 0.1% camphene
• 0.1% methyl eugenol
• 0.1% ethyl salicylate
• 0.1% methyl 5-hydroxysalicylate
• 100.3% total

Source: Frey, 1988.

Sources of illustrations

Gaultheria leucocarpa: Li, H.L., 1978. Ericaceae. In: Li, H.L. et al. (Editors): Flora of Taiwan. Vol. 4. Epoch Publishing Company, Taipei, Taiwan. Fig. 899, p. 18 (flower, stamen, sections); Sleumer, H., 1966. Ericaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana, Series 1. Vol. 6. Wolters-Noordhoff Publishing, Groningen, the Netherlands. Fig. 67, p. 693 (flowering and fruiting branch). Redrawn and adapted by P. Verheij-Hayes.

Authors

L.S.L. Chua & S. Sunarti