Common Name: Sandalwood

General Information

Santalum album is a small, very slow-growing, elegant, evergreen shrub or tree, growing from 4 - 20 metres tall[]. The bole can have a diameter of around 20cm[]. A semi-parasitic plant, it depends on the presence of certain other tree species, especially nitrogen-fixing species, in order to obtain part of its nutrition[, ].
The plant is harvested in large quantities from the wild, mainly for use of its scented wood and as a medicine. It has a very long history of use, being highly valued for its sweet fragrance and used as a medicine, perfume and incense in the East for at least 4,000 years[]. The plant has special significance in Hindu devotional practices, but is also commonly used by Buddhists, Muslims and many other people[, , ]. The tree has many other uses and is often cultivated in parts of tropical Asia and Australia for its essential oil, which is used in perfumery, as a food flavouring etc[].
Fire, grazing and most importantly exploitation of the wood for fine furniture and carving and also oil are threatening the species. Smuggling has assumed alarming proportions. The plant is classified as 'Vulnerable' in the IUCN Red List of Threatened Species(2011)[].

Known Hazards

None known

Botanical References

Range

E. Asia - India, Malaysia.

Habitat

Mostly found in dry deciduous and scrub forests where the vegetation type is a typical monsoon vine thicket growing on pure sand[]. Also found in wet forests[].

Properties

Conservation Status	Vulnerable
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Tree
Height	10.00 m
Growth Rate	Slow
Cultivation Status	Cultivated, Wild

Cultivation Details

Grows in tropical and subtropical areas, usually at elevations below 1,200 metres but occasionally as high as 2,500 metres[]. The reported temperature range for growth is 10 - 38°c, with the optimum between 22 - 30°c[]. It can survive temperatures down to 2°c[]. The reported annual rainfall range for growth is 450 - 2,500mm, with the optimum between 800 - 1,400mm[].
Prefers a fertile, moist but well drained soil in sun or partial shade[]. Prefers a slightly acid soil and a position in full sun[]. Highest quality essential oils are produced when the tree is grown in dry, rocky areas[]. Established plants are fairly drought tolerant[, ]. Dislikes waterlogged soils[]. Prefers a pH in the range 6 - 7, tolerating 5 - 9[].
A semi-parasitic plant, obtaining some of its nutriment from the roots of other plants[]. The plant has green leaves containing chlorophyll, and is thus able to photosynthesize - it relies on host plants only for water and soil nutrients, not for sugars, which it can produce itself []. In a natural situation, the plant seems to rely on nitrogen fixing trees such as Acacia and Casuarina, though it is known to parasitize many other legumes, shrubs, herbs and grasses[]. It normally has more than one host at a time[].
A most probable natural host is Drypetes lasiogyna, observed to be the most prolific species in the vicinity of S. Album[].
The species is spread rapidly through seed dispersal by birds, which feed on the outer fleshy pericarp. Viable seed production occurs when the tree is 5 years old[].
Sandalwood is highly valued for its fragrant heartwood which is used as a timber and source of an essential oil[]. However, because it is very slow growing, taking up to 40 years to develop its heartwood fully, the tree has been overexploited and has become endangered in the wild[].
It is desirable not to clean-weed all round the sandal seedlings, as the roots form haustorial connections with adjoining weed growth[].
It has been suggested that the original source of the incense in India may have been Pterocarpus santalinus (red sandalwood), and that this was gradually replaced by Santalum album after its introduction from Indonesia[].

Edible Uses

The bark is sometimes chewed as an alternative to betel nuts (Areca catechu)[].

An essential oil is obtained from the roots and heartwood[]. It is used commercially as a flavouring in a range of foods including chewing gum, ice cream and bakery products[].

Fruits are edible[, ]. The fruit is a globose, fleshy drupe; red, purple to black when ripe, about 1cm in diameter[].

Medicinal

Sandalwood contains 3 - 6% essential oils (predominantly the sesquiterpenols alpha- and beta-santalol), resin and tannins[]. It is an aromatic, bittersweet, astringent herb that cools the body, calms the mind, relieves spasms and improves digestion[]. It has diuretic, analgesic, antiseptic, expectorant and stimulant effects[, ].
The wood or essential oil is taken internally in the treatment of genito-urinary disorders, fever, sunstroke, digestive problems and abdominal pain[].
A paste of the wood is used externally to treat skin complaints[, ].

Sandalwood oil is little used in modern herbalism, its main application is in aromatherapy[].

Agroforestry Uses:

Santalum album is considered in Indian to be a practical agroforestry species. It is sometimes grown as an ornamental and as a low-branching wind-break, whilst its leaves provide green manure[].

Other Uses

Sandalwood oil, steam distilled from the heartwood, roots, branches etc is an indispensable aromatic material in perfumery, where its outstanding fixative properties and excellent tenacity, blending ability and highly attractive fragrance have made it a basic component of countless perfumes, cosmetics and toiletries[]. It blends well with other essential oils such as patchouli, vetiver, geranium and musk[]. It is also used in soap making and medicines[, ]. All parts of the plant contain these essential oils - which comprise at least 90% sesquiterpene alcohols[].
The roots contain the greatest quantity of oil, with around 6 - 10%[, ], and hence are more valuable[]; the heartwood yields 4 - 8%; the leaves about 4%; the branches 2 - 4%; and the bark around 2%[, ].
An essential oil is also obtained by acid hydrolysis of distilled sandalwood chips and sawdust. This oil differs in scent and appearance from true sandalwood oil[].
Powder from the heartwood, mixed with gum arabic and saltpetre and often with other aromatic materials, is used to make incense sticks[, , ]. It is also burnt as perfumes in houses and temples, or is ground into a paste and used as a cosmetic[, ]. It is put in sachets and placed in linen cupboards etc for scenting clothes[].
Finely ground sandalwood, mixed with water, is rubbed on the body for its cooling effect[].

A compound extracted from the bark exhibits hormone activity in insects, disrupting their development. It also has a chemosterilant effect, but is not used commercially[].

The bark contains about 12 - 14% tannin and has good potential in the tanning industry[].

The seeds yield a red drying oil that is mainly used as a lamp oil and can be used in the manufacture of paint[, ].

The fresh leaves yield a pale yellow wax[]. It has a melting point of 30°c and contains 75% non-saponifiable compounds[].

The wood, which weighs 870 kg/cubic m, is heavy, hard, durable and strong, but difficult to split[, ]. It is not attacked by termites[]. Odourless when freshly cut, it becomes strongly aromatic as it seasons[]. Its close grained heartwood is much used for ornamental and carving work[, ]. Formerly, in China the most expensive coffins were made of sandalwood, while in India it was the preferred wood for funeral pyres[]. Even today it is customary to add at least a single piece of sandalwood. When supplies became scarce, sandalwood from Australian Santalum species was used for such purposes. Larger pieces of heartwood are now mostly used for wood sculptures and carvings[].
The wood has been used as a fuel but is generally considered too valuable for this purpose[]. It is traditionally burnt at Buddhist funerals and is also ground into a powder to make the paste used in Hindu caste marks[].

Propagation

Seed - pre-soak in a solution of 1:9 bleach to water and germinate in a free-draining but moisture retentive sterile medium such as vermiculite at 16 - 20c[]. Pot on when the roots are about 4cm long, placing each plant in a free-draining compost together with a potential host plant[].

Most natural seedlings of sandal are found growing in the middle of thorny bushes, where the birds have dropped the seeds. Artificial propagation is easily done by directly dibbling freshly collected ripe seeds in worked up soil patches, with the onset of the monsoon, in the middle of the nurse bushes or in protected patches. Fresh seed has a dormancy period of 2 months. Manual scarification or gibberellic acid can break this. They germinate in about 8 - 14 days, with a germination rate of 70%. Lantana camara, commonly found growing in scrub forests in areas suitable for sandal, acts as a good nurse to the seedlings in the early stages. Planting of container-raised seedlings or branch cuttings is also successful; trees are raised with a host plant, for example Cajanus cajan, Senna siamea, Terminalia, Lagerstroemia, Anogeissus, Dalbergia, Pongamia, Albizia and Acacia species. Seeds can be sown in polythene bags along with the sandal seeds and watering is once a day. Sandal seedlings attain a height of 15 - 20 cm by planting time and are planted out in the field along with the host plant. Seedling growth is rapid with 20 - 30 cm obtained at the end of the 1st year and 60-70 cm at the end of the 2nd year. Root suckers are produced when roots are exposed or injured. The nursery phase to raise sturdy 30 cm plants is usually 8 months. Primary host species are grown alongside the seedlings in each pot. S. album has been propagated vegetatively by tissue culture, branch cuttings and cleft grafting. Direct sowing in the fields is used in some situations. Secondary host species should be well established on the planting site before planting. Acacia, Casuarina, Paraserianthes and Sesbania spp are amongst a wide range of successful hosts[].

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