The evergreen sandalwood tree is native to India, Australia, and many regions around the Pacific and Eastern Indian Ocean, including Hawaii, New Caledonia, Vanuatu, Indonesia, and other Pacific Islands. These trees range in size from small shrubs to trees of around 12 meters (40 feet) tall. The sandalwood tree also possesses the unique ability to thrive in many diverse climates, including deserts in Australia, monsoon climates in India, eastern Indonesia, and Vanuatu, and subtropical climates in Hawaii and New Caledonia (Pacific Island Agroforestry [PIA], http://www.agroforestry.net/images/pdfs/Santalum-a-y-sandalwood.pdf, 2006)
According to a recent article on the genetics of sandalwood trees in the American Journal of Botany, research indicates that although the tree now has a widespread range, sandalwood originated in Australia. While the exact method of the sandalwood’s chance dispersal millions of years ago is still undetermined, the tree’s presence across multiple oceanic islands and continents today is most likely due to natural forces such as ocean currents.According to the American Journal study, it’s probable that ocean currents carried sandalwood seeds long distances. Additionally, migrating birds, who are attracted to the sandalwood’s red, purple, and black fruits, most likely ate and then deposited the fruits on distant shores. The sandalwood tree’s fruit possesses a tough, thick exterior layer that would have protected it from being completely destroyed through digestion and other damage during the long journey (AMJB, http://www.amjbot.org/content/94/6/1028.full, 2007).
The sandalwood is part of the same plant family as mistletoe (in the family of Santalaceae) and is classified as a hemi-parasitic plant, indicating that it uses a unique strategy to survive (http://www.parasiticplants.siu.edu/Santalaceae/,2013). Hemi-parasitic plants such as sandalwood spread their roots wide and perform “root grafting” with a host plant, which means that their roots attach and form connections with the host’s roots in order to exchange nutrients. Thus, they obtain part of their water and nutrients from the host and part of their nutrients from photosynthesis (PIA, http://www.agroforestry.net/images/pdfs/Santalum-a-y-sandalwood.pdf, 2006).
The most well-known and valuable species is Santalum album: Indian, or white, sandalwood. Native to India, Indonesia, China, and the Philippines, this species has a slightly different appearance than other Santalum species, often forming a dense shrub around 4 meters (12 feet) high with glossy leaves up to 7 cm long (International Union for Conservation of Nature [IUCN],
The Santalum album also has the highest oil content (6-7%) among sandalwood species (Food and Agriculture Organization of the UN [FAO],
http://www.fao.org/docrep/016/ap001e/ap001e15.pdf, 2011)as well as the highest santalol content, around 70-90% (India Times, http://timesofindia.indiatimes.com/city/bangalore/Demise-of-sandalwood/article show/12078008.cms, 2012).
Because of these properties, Indian sandalwood has been prized and harvested since ancient times. Today, however, this species is classified as a “vulnerable species,” due to over-harvesting of trees in their natural environment, habitat conversion, and pressures on the land for other uses (IUCN,http://www.iucnredlist.org/details/31852/0, 2013.) Subsequently, Indian sandalwood and its essential oil have become expensive and rare, and the Indian government has increased its efforts to protect this valuable resource.
In addition to S. album, many other species of sandalwood are used for their valuable wood and oil. S. austrocaledonicum, native to the islands of New Caledonia and Vanuatu, is used for woodworking, and its oil is sold as the most ubiquitous sandalwood essential oil. Fiji’s S. Yasi contains wood and oil similar to that of S.album, and also produces sandalwood essential oil. Additionally, the Australia sandalwood (S. spicatum), once over-harvested but more recently mass-planted, has now become a leading source for Australian sandalwood essential oil, though this species’ oil is not regarded to be as fine or as highly prized as Indian sandalwood oil and the oil from other species (FAO, http://www.fao.org/docrep/016/ap001e/ap001e15.pdf, 2011). The heartwood of the Australian sandalwood produces around 3-3.5% oil, compared to Indian sandalwood’s (S. album) 6-7% oil (Western Australian Sandalwood Plantations [WASP], http://www.wasandalwood.com/index. php?id=88).
Although not major producers of sandalwood oil, there are many more species of sandalwood trees. Some of these other species are also harvested for their wood and/or distilled for their essential oil. There are around 15 extant species of sandalwood, listed with their geographic regions below (FAO, http://www.fao.org/docrep/016/ ap001e/ap001e15.pdf, 2011) (Germplasm Resources Information Network [GRIN], http://www.ars-grin.gov/cgi-bin/npgs/html/splist.pl?10699, 2014):
Common names: East Indian sandalwood, white sandalwood, white saunders, yellow sandalwood, yellow saunders, bois santal, santal blanc, santal des Indes, Sandelholzbaum, chandan, sándalo blanco, sándalo Indias orientales, vitt sandelträd
Common names: West Australian sandalwood, australiskt sandelträd.
Synonyms: Eucarya spicata, Fusanus spicatus
Common names: burn-burn, sweet ouandong, sweet quandong, western quandong
Synonyms: Eucarya acuminate, Fusanus acuminatus, Mida acuminate
Common names: Santal jaune, Santal rouge
Subspecies: Santalum austrocaledon icum var. austrocaledonicum, var. minutum, var. pilosulum
Common names: coast sandalwood
Common names: iliahi, lanai sandalwood
Subspecies: Santalum freycinetianum var. lanaiense, var. pyrularium
Subspecies: Santalum haleakalae var. haleakalae, var. lanaiense
Subspecies:Santalum insulare var. mitiaro, var. insulare, var. alticola, var. raiateense, var. marchionense, var. deckeri, var. raivavense, var. margaretae.
Common names: yasi (Fiji), ahi (Tonga), asi manogi (Samoa)
(PIA, http://www.clshade.net/agroforestry/tti/Santalum-a-y-sandalwood.pdf, 2006).Aside from today’s existing sandalwood species, the species S. fernandezianum, native to the Juan Fernández Islands, became extinct around 1908 after several decades of over-harvesting (IUCN, http://www.iucnredlist.org/details/30406/0, 2013).