Changes

* ''Styrax benzoin'' Dryand., Philos. Trans. 77(2): 308, t. 12 (1787), synonyms: *''Benzoin officinale'' Hayne (1841), *''Cyrta dealbata'' Miers (1851), *''Plagiospermum benzoin'' Pierre (1892).

* ''Styrax paralleloneurum'' Perkins, Bot. Jahrb. 31: 484 (1902), synonym: *''S. sumatranus'' J.J.Sm. (1917).

* ''Styrax tonkinensis'' (Pierre) Craib ex Hartwich, Apoth. Zeit. 28: 698 (1913), synonyms: *''Anthostyrax tonkinense'' Pierre (1892), *''Styrax macrothyrsus'' Perkins (1902), *''S. hypoglaucus'' Perkins (1902).

*General: *benzoin tree (En)

* ''S. benzoin'' : *Sumatra benzoin tree, gum benjamin tree (En)

* ''S. paralleloneurum'' : *Sumatra benzoin tree, gum benjamin tree (En)

* ''S. tonkinensis'' : *Siam benzoin tree, Lao benzoin tree (En)

Benzoin is a balsam obtained by wounding the stem cambium of several ''Styrax'' species. It finds extensive use worldwide as incense and in the flavour, fragrance and pharmaceutical industries. In volume terms, Sumatra benzoin (the product of ''S. benzoin'' and ''S. paralleloneurum)'' ) is the most important type of benzoin and it is used for incense in e.g. the Middle East, North Africa, parts of Asia and the Indian sub-continent. Most commonly, small or crushed pieces of the raw benzoin in semi-processed block form are simply placed on an open fire, either in the house or in the place of worship. Sometimes it is mixed with other natural fragrance resins such as frankincense ( ''Boswellia'' spp.), myrrh ( ''Copaifera'' spp.) and storax ( ''Liquidambar orientalis'' Mill.). Extracts of Sumatra benzoin are used to produce fragrances for joss sticks. In Java, benzoin is applied for ritual ceremonies related to death or spirits. Siam and Sumatra benzoin are both used for flavour and fragrance purposes but usually satisfy different parts of the markets. Siam benzoin has a rounder, more vanilla-like odour than Sumatra benzoin, which is harsher to the nose. The better grades of benzoin are extracted for the manufacture of fragrant products. These include personal health care products (e.g. toilet soaps, shampoos, body lotions, creams) and household and other products (e.g. liquid soaps, air fresheners, washing detergents). Although there is occasional overlap in end-use, the pleasant, rounder fragrance of the more expensive Siam benzoin is generally found in fine fragrances (perfumes and colognes) and the more expensive soaps. Although benzoin contributes its own fragrance to the final, formulated product, one of its important functions is to serve as a fixative for the other fragrance materials, increasing the tenacity and preventing loss of the middle and top notes of the more volatile components. 

In Palembang, South Sumatra, the benzoin plantations were replaced by para rubber ( ''Hevea brasiliensis'' (Willd. ex Juss.) Müll.Arg.) in the 1920s. The Tapanuli area around lake Toba, North Sumatra, however, is too high for para rubber and continues to be important for benzoin cultivation and production.

It is difficult to find reliable data on properties of benzoin. Samples may or may not be representative. For the two best balsam grades of ''S. benzoin'' ("red benzoin") and ''S. paralleloneurum'' ("white benzoin") the following data are an indication of their chemical content: insolubility in ethanol 1.2-2.8% and 1.3-3.7%, ash content 0.09-0.17% and 0.03-0.07%, cinnamic acid 0% and 24.5-30.6% and benzoic acid 26.2-27.2% and 11.5-12.9%. Sumatra benzoin is usually 75% soluble in ethanol, but when of very high quality it is 95% soluble. As Sumatra benzoin is sold in blocks its quality is variable, partly because it includes pieces and dust of "damar", the exudate from ''Dipterocarpaceae'' . The aromatic compounds of the different benzoin species (balsamic acids (i.e. benzoic acids and cinnamic acids), vanillin, cinnamic-, p-coumaryl- and coniferylalcohol) are probably products of an injury-induced change to the lignin metabolism. It is unknown whether sumaresinol acid occurs in the bark or wood of non-injured trees. Unlike many other balsams, benzoin produces negligible amounts of essential oil on distillation.

Paleness and purity (without extraneous matter i.e. high alcohol solubility) are important indicators of quality. A tentative FAO/WHO specification exists for "benzoin gum" as a food additive: for Sumatra benzoin and Siam benzoin the ethanol solubility should be respectively75% and90% and the acid-insoluble ash should be respectively1respectively 1% and0and 0.5%. Pharmaceutical uses of benzoin generally require compliance with national pharmacopoeia specifications and these vary according to the pharmacopoeia and the type of benzoin. Loss on drying should usually be10be 10% for both types of benzoin, but alcohol solubility is70is 70-80% for Sumatra benzoin and90and 90-98% for Siam benzoin. Balsamic acid content is important, and both types of benzoin are usually required to contain a minimum of 25% acids (calculated as cinnamic acid for Sumatra benzoin and benzoic acid for Siam benzoin). Total ash and acid-insoluble ash are also specified in some pharmacopoeias. The wood is dull red to pale brown with irregular white flecks, grain very coarse, 470-710 kg/m³at 15% moisture content, rather soft, moderately strong and non-durable to slightly durable.

*Evergreen shrubs or trees, bole usually with small buttresses, excreting a fragrant balsam on being bruised; bark surface smooth to vertically cracked or finely fissured, inner bark soft, brown to deep red, pink or purplish-red, sapwood white. *Leaves simple, spirally arranged, without stipules; petiole grooved; blade ovate to oblong or lanceolate, margin entire or shallowly serrate-dentate, apex acuminate, secondary veins in 5-13 pairs, underside with white stellate hairs or scales. *Inflorescence a terminal or axillary raceme or leafy panicle; flowers .*Flowers regular, bisexual, 4-7-merous; calyx campanulate or cup-shaped, free or the base connate to the ovary, truncate or rarely 4-5-dentate, persistent in fruit; corolla connate at the base (1-2 mm) with annular staminal tube, deeply 4-7-lobed, subfleshy; stamens twice the number of petals, in one whorl, basally fused to each other and to the corolla tube, staminal tube up to 4 mm long, anthers splitting lengthwise; ovary superior, imperfectly 3-locular with 1 to few ovules per cell, densely hairy, style filiform, 3-angular, stigma capitate or indistinctly 3-lobed. *Fruit a globose or depressed globose drupe, dehiscent or indehiscent, pericarp 3-5 mm thick. *Seeds 1(-2), attached basally; testa with 2 layers, the outer layer thick and stony and the inner one membranous. *Seedling with epigeal germination; cotyledons subfleshy; hypocotyl with purple flecks; first pair of leaves opposite, subsequent ones alternate to spiral.

* ''S. paralleloneurumbenzoin'' . *Tree, 58-35 34 m tall, trunk 2310-60 100 cm in diameter, young twigs grey. *Leaf blade 68-16 13 cm × 2-7 5 cm, underside undersurface with white woolly indumentum of stellate hairs and golden-brown stellate scales, veins in 67-8 13 pairs with distinct transverse veins. *Inflorescence a panicle, up to 11 20 cm long, with droopingbut usually smaller than the leaves.*Flowers fragrant, violet-scented flowerswhite; pedicel up to 4-6 mm long; corolla tube 4 1-2 mm long, lobes 9-12 mm × 2-3 .5 mm. *Fruit globose, 2-3 cm in diameter with large cupular calyx× 2 cm, indehiscent. *Seed shiny dark subglobose, 1.5-2 cm in diameter, dull pale brown.

 ''S. paralleloneurum''.* Tree, 5-35 m tall, trunk 23-60 cm in diameter.*Leaf blade 6-16 cm × 2-7 cm, underside with white stellate hairs and golden-brown stellate scales, veins in 6-8 pairs with distinct transverse veins.*Inflorescence a panicle, up to 11 cm long, with drooping, violet-scented flowers; pedicel 4-6 mm long; corolla tube 4 mm long, lobes 12 mm × 3 mm.*Fruit globose, 2-3 cm in diameter with large cupular calyx, indehiscent.*Seed shiny dark brown.  ''S. tonkinensis'' . *Tree, up to 20 m tall, trunk up to 40 cm in diameter. *Leaf blade 5-20 cm × 2-12 cm, underside with white stellate hairs, secondary veins in 7-9 pairs with distinct transverse tertiary ones. *Inflorescence a panicle, up to 18 cm long, with white flowers up to 1.5 cm long; pedicel 3-5 mm long; corolla tube 2.5-3 mm long, lobes 6-8.5 mm × 2-3 mm. *Fruit ovoid, 1 cm × 0.7 cm, dehiscent with 3 valves. *Seed orange.

The following ''Styrax'' species have also occasionally been reported to produce benzoin; at present they are usually more important as ornamentals: *''S. benzoides'' Craib - tree, 10-15 m tall, occurring in Thailand, Laos and Vietnam; especially formerly an important source of Siam benzoin; *''S. crotonoides'' Clarke - tree, up to 30 m tall, occurring in Peninsular Malaysia and Vietnam; *''S. japonicum'' Siebold & Zucc. - shrub, 2-3 m tall, occurring in Japan, northern China, Taiwan and (rarely) in the Philippines; *''S. officinalis'' L. - shrub or very small tree, occurring in the Mediterranean; *''S. ridleyanum'' Perkins - tree, 30 m tall, occurring in Burma (Myanmar), Peninsular Malaysia and Sumatra; *''S. serrulatum'' Roxb. - tree, 6-12 m tall, occurring from India throughout continental South-East Asia to Taiwan.

''Styrax'' prefers mixed primary forest with rich clayey soils. It is less common in dense secondary forest. ''S. benzoin'' is found at altitudes of 100-700(-1600) m, outside Malesia it is restricted to 200-500 m. ''S. paralleloneurum'' occurs at (575-)800-1700 m altitude. In Laos, ''S. tonkinensis'' occurs predominantly at (600-)800-1600 m elevation, while in Vietnam it occurs mostly below 1000 m. ''S. tonkinensis'' is a light-demanding species and in open habitats it often occurs in the upper storey. Seedlings cannot survive shade in dense forest. Benzoin trees need well-drained soils, as excessive water leads to dying back. In ''Styrax'' 's ’s area of natural distribution the mean annual rainfall is usually 1500-2200 mm, with no distinct dry season (or only a few drier months). However, under cultivation it will thrive in areas with mean annual rainfall of 1300 mm and 3-6 dry months. Mean annual temperature in its natural range is 15-26°C but it can tolerate extremes of -4°C and +45°C for a short period. The success of ''S. tonkinensis'' owes much to human activities and to its pioneer characteristics: fire accelerates seed germination and many stands occupy sites previously used in shifting cultivation. Bamboo is one of the most common associates of ''S. tonkinensis'' and in natural regeneration in shifting cultivation systems ''Imperata cylindrica'' (L.) Raeusch. and ''Erianthus arundinaceus'' (Retz.) Jeswiet are common undergrowth. 

'''== Management''' == The forest in Tapanuli region, North Sumatra, consisting mainly of Merkus pine ( ''Pinus merkusii'' Jungh. & de Vriese), has gradually been modified into a forest with a high density of benzoin trees represented by a wide range of sizes. At an elevation of 1300 m ''S. paralleloneurum'' is dominant and, at lower altitudes ''S. benzoin'' is prominent. The estimated density of benzoin trees is about 1375/ha of all sizes. Benzoin plantations have also been established by sowing before upland rice is sown. In the early stages benzoin trees need shading. Recently, there have been experiments with planting coffee under large benzoin trees while also maintaining a few benzoin seedlings and saplings.

In Vietnam, nitrogen is given in 3 applications of 20 g per plant within one month of planting ''S. tonkinensis'' . Plantations should be kept weed-free in the first two years by regularly removing of ground cover and cultivating the soil in a 50-60 cm radius around each plant. In plantations for pulp production with a rotation of 10 years, two thinnings (at 2 years and 3 years old) are required to achieve a final density of 600-800 stems/ha. Under favourable conditions a mean height of 18-25 m and diameter at breast height of 20-24 cm may be achieved after 10 years.

A defoliator ( ''Fentonia'' sp., Lepidoptera: ''Notodontidae'' ) causes damage to thousands of hectares of ''S. tonkinensis'' plantations in Vietnam every year. The larval stage has four instars, with the third and fourth instars being most damaging, each larva consuming 6-7 g of leaves per day. Control measures involving chemical sprays have been recommended but ''Fentonia'' also has several natural predators, including two ant species ( ''Oecophylla smaragdina'' and ''Cremastogaster'' sp.) and two bees ( ''Anastatus'' spp.) which need consideration. In Laos young trees are attacked by fungi and various insects (crickets, termites, stemborers), which still need to be identified. 

The balsam is only produced when the cambium is wounded, probably in newly formed cells at the end of rays in the xylem. Tapped trees generally exude throughout the year, except during periods of heavy rainfall. Tapping of Sumatra benzoin trees may start when 7 years old. After cleaning and smoothening the bark a piece of bark (2 cm wide and 2-4 cm long) is loosened from the wood with a tapping chisel and the bark is lightly beaten. The tapping wounds are made on two sides of the stem and from its base up to 3-5 m (reached by climbing the tree). Occasionally the balsam exudes so fast that it is necessary to use a container to collect the fluid. When harvesting ''S. paralleloneurum'' , the balsam under the loosened piece of bark is cut from the tree and graded into "large almonds" ("mata kasar", "mata besar") and "small almonds" (or "mata halus"). Then the wood of the tapping wounds is exposed, the bark of the borders of the wounds is cut and the balsam is scraped off after a few weeks ("jurus"). Three months later the rest of the balsam is collected ("tahir"). The second and third harvests yield a brownish sticky balsam, used to prepare the trade product. ''S. paralleloneurum'' in North Sumatra is tapped from June to September. Once or twice a year the trees are tapped again, making new wounds above the old ones where wood is exposed. Although callus formation is rare, the soft wood is rarely attacked by wood-rotting fungi or wood-boring insects. The balsam of ''S. benzoin'' does not harden but remains sticky. It oozes from the wound and forms long threads on the stem, resembling yellow rice straw (hence "haminjan durame"). At the first harvest the bark and sticky balsam are removed ("parung") and generally the threads formed on the stem are added to this grade. The second quality is "longkap" and the third one with many impurities is "jarir". Tapping of planted ''S. benzoin'' trees in Java has not been successful.

* "mata kasar" ("big eye"), first quality

* "mata halus" ("soft eye"), second quality, 1-2 cm, yellowish white

* "jurus/jarir", brown with yellowish white pieces, mixed with bark and other impurities

* "tahir", similar to "jurus" and usually mixed with it

* "barbar/laklak" which is the bark that has been removed from the other grades during cleaning

* "abu", ("dust"), produced from broken "almonds", "jurus" and "tahir".

 In contrast to Siam benzoin from Laos, which is sold only in its whole, cleaned form, most Sumatra benzoin enters world trade in a processed form known as "block benzoin". Essentially, block benzoin consists of light-coloured pieces embedded in a much darker matrix. However, the light-coloured pieces of benzoin are present only in the higher grades; in the majority of cases they are pieces of "damar" (resin from ''Dipterocarpaceae'' ). Damar is considerably cheaper than benzoin and readily available from Indonesia and elsewhere. It acts as a binder to make blocks of benzoin that are easier to transport and handle. Most benzoin intended for incense is traded in this form, and damar improves the burning quality as does the presence of powdered bark, although the scent of damar is inferior. The British Pharmacopoeia specification (which relates to Sumatra benzoin) requires damar to be absent and there is a test to check this. Preparation of block benzoin involves adding damar to low grade benzoin according to a well-tried formula, and cooking it briefly in hot water. The wet mixture is then transferred to shallow wooden boxes lined with cotton, and surplus water is squeezed out. The boxes are set aside to cool so that their content solidifies.