Threatened / Endangered Essential Oil Species

By:  Kathy Sadowski, MS in Aromatherapy, Registered Aromatherapist (ARC), Professional NAHA and AIA Member, LMT

This article originally appeared in the NAHA Journal (Autumn, 2017) and it is republished here according to the NAHA Writer Guidelines 2019-20 copyright statement.

Introduction

The growing popularity of herbal medicine and essential oils has increased the demand of multiple healing plants to the point of serious over harvesting.   Essential oils, stored in the tiny secretory structures, require a large amount of plant material, up to 100 times or more, to make one tiny bottle of oil.  For those plants whose population is dwindling to the point of scarcity, it is unethical to harvest and produce oils in a way that jeopardizes their earthly existence.  This paper will focus on identifying and describing specific plant species used for making essential oils that are in serious risk of over harvesting.

Below is a list of plants who have species or subspecies in danger.  Please visit the websites discussed for more detailed and up to date information before purchasing essential oils from these botanicals.  It is the duty of a responsible consumer to reduce the demand on vulnerable species.  The main species of concern include:

• Frankincense (Boswellia carteri, B. sacra, B. frereana and multiple other Boswellia species)
• Rosewood (Aniba rosaeodora, multiple Ocotea species, and multiple Dalbergia species)
• Sandalwood (Santalum album, S. spicatum, S. austrocaledonicum, and multiple other Santalum species along with Osyris lanceolata and Pterocarpus santalinus)
• Spikenard (Aralia racemosa, A. californica and other Aralia species along with Nardostachys grandiflora and N. jatamansi)
• Agarwood (Aquilaria crassna and all Aquilaria species along with all Gyrinops species)
• Cedarwood Atlas (Cedrus atlantica, other Cedrus species, many Juniperus species, and Widdringtonia whytei Rendle)

Research Websites:

• www.iucnredlist.org – This is the number one authority for information on species in danger.  Please note the following terms in which this organization classifies threatened species that will often be mentioned in this paper:  “Near Threatened,” “Vulnerable,” “Endangered,” “Critically Endangered,” “Extinct in the Wild,” and “Extinct.”
• www.cropwatch.org – Burfield provided a wealth of information (2005 – 2010) on aromatic plant species at risk.  However, this website is no longer available.
• www.unitedplantsavers.org – This group focuses on threatened American plant species.
• www.cites.org – The Convention on International Trade in Endangered Species of Wild Fauna and Flora creates international agreements between governments to protect species.

Additional websites that provide information about at risk plant species include:

• www.saveplants.org
• www.traffic.org
• www.asnapp.org
• www.saveourspecies.org
• www.phytotrade.com
• www.peopleandplants.org

Frankincense (Boswellia sacra, B. frereana and other Boswellia species)

Also called Olibanum, Boswellia sacra, is classified as “Near Threatened” on the 2017.1 IUCN Red List (1).  This sacred tree is found in Northern Somalia, Oman, and Yemen (2).  In some areas, like Oman, it is “Critically Endangered” (3).  Several Boswellia species located in Yemen have a dangerously declining habitat and were listed as “Vulnerable” on the IUCN Red List of Threatened Species in 2017, such as B. ameero, B. bullata, B. dioscoridis, B. elongate, B. nana, B. popoviana, and B. socotrana (4).  B. ovalifoliolata from India and B. ogadensis from Ethiopia are also vulnerable (5, & 6).  This tree resin has been a highly valuable plant extract since ancient times, with the Horn of Africa trading it as a lucrative commodity for 2,000 years (7).  Today, it is used in Western medicine for inflammation, and as an anti-carcinogenic (8).  Further studies indicate it may be effective in treating bladder cancer (9).  It is harvested by precisely cutting into the bark and allowing the resin to slowly ooze out and then solidify; with the cuttings repeated two or three times in the five month harvest season (7).  Boswellia papyrifera genetic variety is dwindling in Western Ethiopia and conservation strategies need to be implemented (10).

Somililand, which is not technically a country, is an area where frankincense is especially overharvested and under protected.  Here, the resin is purchased from the harvester by a middleman for an extremely low price, then sold in the Middle East for a much higher price to an international market.  Thus, the Somali farmer is exploited with no government control of frankincense sales.  Rising food prices and scarce opportunity for other jobs in the area has a negative effect on the trees with illegal harvesting beyond the season and excessive cutting of the bark. The price to pay for this valuable resin overharvesting is the life of the trees (7).  Further, drought conditions and no government to protect the trees is an issue, but designating the forest area as “Protected” would help the trees (7). 

An additional issue associated with frankincense is the exploitation of poor people for labor.  It is The Horn of Africa’s biggest export after livestock, with an estimated 10,000 families financially dependent on the crop (10).  The women process the resin after it is harvested by the men, typically sitting on a concrete floor 12 hours a day, and making 50 cents to two dollars a day (7).  Working with Fair Trade organizations to have frankincense certified may help set a fair price for harvesters and sustain the trees (7).  Creating a harvesters’ cooperative will further promote fair trade, reduce underbidding, and set sustainability standards (7). 

Rosewood (Aniba rosaeodora, genus Dalbergia ssp., and genus Ocotea ssp.)

Rosewood has a rich burgundy color and is used in making high-end furniture, musical instruments, and oil extracts.  It is a South American plant whose precious oil is known to have been used in famous perfumes like Chanel 5, Presenced’une Femme, Trussadi Skin, and Lagerfield Jako (11). Aniba rosaeodora is listed on the 2017 IUCN Redlist as endangered and is also listed along with 19 Dalbergia ssp. on CITES (1 & 12).   Many Ocotea species are “Near Threatened,” “Vulnerable,” “Endangered,” or “Critically Endangered” on the 2017.1 IUCN Red List (1).  Critically endangered are: O. harrisii, O. lancilimba, O. monteverdensis, and O. pachypoda, endangered are O. basicordatifolia, O. jorge-escobarri, and O. staninoides, and ten Ocotea species are listed as vulnerable (1).  Unfortunately, trees of all sizes are harvested and destroyed for rosewood oil extraction and other uses (13). In the Atlantic rainforest of Brazil, heavy harvesting based on a high value of timber and essential oil has rendered many species “Vulnerable” to “Extinct.”  Fragmented and reduced populations of these species are causing the loss of rare alleles; like inbreeding, this will result in a reduction of genetic diversity (14).  Further, it is important that even small populations on fragmented pieces of unprotected land play a role in species survival and improved genetic diversity (14).  Illegal logging is also a problem, with issues like cross-border logging in the Cambodian–Lao region (15). 

As for Ocoetea porosa, selective logging in the Southern Brazilian state of Parana over the past century may have contributed to a lower quantity of the larger trees, which could impact the rate of reproduction and cause local extinction (16).  The canopy openness and gap openings in a cohort composed of more juvenile plants dangerously creates less height variety for the species (16).  Other species in danger include O. obtusata, considered “Critically Endangered,” and O. mascarena, whichis “Endangered” by the country of Mauritius (3).

With the CITES listing of Brazilian rosewood, logging then shifted to Madagascar (17).  In Madagascar, Malagasy rosewood, including D. baronii, D. louvelli, and D. madagascariensis, is one of the most sought after hardwood crops in the world (18).  Illegal logging is happening at an alarming rate and severely threatening Madagascar rainforests. Local residents are cutting for a very low profit and selling to criminal exporters who have corrupted officials (19).  This happens even though the Marojejy National Park has been established as a UNESCO World Heritage Site (18).  Madagascar is one of the world’s key threatened bio diverse areas with an immediate risk for rosewood species extinction and has been recently protected under CITES.  Even though the Malagasy government has prohibited rosewood logging and export as of 2010, weak penalties and poor enforcement prolong the problem (17).  The rosewood logging involves cutting down hundreds of unused trees to get to the bigger trees, ratifying landscapes, decreasing soil fertility, and increasing potential fires; thus affecting the local ecosystem of many other plant and animal species (17).

Multiple other species of rosewood are at risk.  Siamese rosewood (Dalbergia cochinchinensis Pierre) of Thailand and Laos is in very high demand and has been illegally logged for the past few decades, affecting genetic diversity (63).  Aniba rosaeodora is “Endangered” on the 2017.1 IUCN Red List (1) and found in South America, with trees of all sizes indiscriminately harvested illegally (13).  Multiple dalbergia species are “Endangered,” “Vulnerable,” and “Near Threatened” due to overharvesting by the perfume industry; D. oliveti and D. cochinchinensis are listed as “Priority Tree Species for Gene Conservation” in Camboida, and in Nepal, D. latifolia is a “Vulnerable” species (11 & 3),  D. sissoo is considered a “Threatened” tree by the country of Pakistan, D. retusa is considered “Vulnerable” by the country of Nicaragua, and D. retusa is considered “Endangered” by Panama (3).

Sandalwood (Santalum album, S. spicatum, and S. austrocaledonicum)

S. album is listed as “Vulnerable” on the 2017 IUCN Red List (1).  Exploitation has drastically affected this parasitic tree, with the rate of extraction far exceeded the rate of growth for many years (11).  Spike disease, grazing animals, and fire have further been a problem for S. album, especially in the Timor Islands (64).  Australian sandalwood (S. spicatum) has been used as a replacement but has also recently been over-exploited and historicaly used by major perfume companies (11).    Heavy international demand with poor regulation contributes to the problem (20). Further, due to a low supply and high demand, prices have skyrocketed, increasing illegal harvesting (21). Synthetic fragrances have been manufactured to help reduce the demand on this scarce resource.  In addition, to save this plant, a key issue that needs addressed is the low genetic variability, with inbreeding that causes important missing alleles and poor sexual reproduction (22).

 Before the 1900s, sandalwood was used mainly to burn incense and for attars and oils.  Then, in 1918, India’s first sandalwood oil factory was established, using the heartwood from the tree to manufacture shampoos, soaps, perfumes, and cosmetics at an industrial scale (23).  From 1950-1970 about 480,000 S. album trees were harvested per year in India’s southern state of Karnataka.  Then in 1974, only a fraction of the trees were left in Karnataka and the species was near extinction, with the government putting a halt to harvesting (23).  Smugglers then made big money on the tree, with one man in particular, Veerappan, who became very rich off the illegal trade, thus becoming an embarrassment to Indian police (23).  Before 9/11, the hunt for Veerappan was the largest and most costly in Asia.  He was finally killed by police in 2004, but other smugglers have since taken his place. (23)

Santalum album Linn, in the East Nusa Tenggara of Indonesia, is an important natural commodity representing about 40% of the Province’s income from 1986-1992 (24).  In the past two decades, the alarming decrease in tree population has forced a governmental ban on harvesting from 1997 – 2003 (24).  Local farmer participation in cultivating sandalwood has been low because of strict government policies, with the Regional Regulation Act No. 16/1886 making all sandalwood property of the government regardless of if it was grown on private or state lands (24).  Some districts have since issued new regulations giving more rights to the people, including the cutting and selling of trees, thus encouraging planting (24).

Unsustainable harvesting in the Timor islands with farmers using uncontrolled fire as a method to clear land is a key threat to that local subspecies (19).  Unfavorable legislation in the Timor Islands that is trying to protect the trees, discourages farmers to plant because if they illegally cut or mistreat the sandalwood, they could face criminal charges.  This provides a disincentive for local people to help grow more trees (19).

In Sri Lanka, boundary demarcation, declared conservation forests, and increased park staff where implemented to protect and conserve sandalwood, but fire and grazing continue to be a main cause of destruction.  In 2010, an effort was made to education local farmers of the damage caused by fire and grazing and the importance of the sandalwood to future generations (25).

S. austrocaledonicum from the islands of Vanuatu and New Caledonia is of serious concern, with little remaining of its natural habitat.  During the 1840’s, sandalwood traders discovered these trees and began overharvesting (26).  In 1987, the government restricted quantities logged, but the land was never properly reforested due to disputes of ownership (26). 

Below is a list of more sandalwood species in danger:

• All Santalum species of Hawaii are on the “At Risk” list of United Plant Savers (27).  
• S. fernandezianum of the Juan Fernandezianum Islands has a status of “Extinct” by the WCMC (11). 
• S. freycinetianum of Polynesia is “Endangered” with a need for a moratorium on tree cutting and land conservation (28) and S. insulare is “Vulnerable,” and the only other sandalwood species of Polynesia (29).
• S. lanceolatum is “Endangered” in parts of Australia (22).
• S. macgregorii is “Endangered” on the 2017.1 IUCN Red List (1).  Located in Papua New Guinea, there are very few mature trees due to overexploitation (30).
• Santalum yasi has been overharvested in Fiji and Tonga, causing a low density and small size of adult trees (31).
• Osyris lanceolata is “Endangered” in Kenya and declining in Tanzania; and has been listed on CITES since 2013 (12).
• Pterocarpus santalinus, red sandalwood,of India is “Endangered” on the IUCN 2017.1 Red List and trade is monitored through CITES with new plantations being established (1, 32 & 12).

Spikenard (various Aralia and Nardostachys species)

Rhizomes of the spikenard plant are used in essential oil for insomnia, stress, and tension with the drug industry using it for various degenerative diseases (33).  CAMP reported a population decline in India of 75-80%, classifying the plant as “Endangered,” with biodiversity under serious threat (34).    Exports of the plant have been banned, resulting in an absence of commercial cultivation that has led to untrained extraction, habitat destruction, and premature harvesting.  This, along with an increased market price, has resulted in heavy adulteration that creates an essential oil without the same medicinal constituents (35).

A. chinensis, A. debilis, A. javanica, A. malabarica, and A. tibetana, areall on the 2017.1 IUCN Red List as “Vulnerable” (1).  A. racemosa and A. californica are on the “To Watch” List of United Plant Savers (27).  Nardostachys grandiflora (Jones) DC of the Himalayas was banned for export from Nepal in 1993, and listed in CITES in since 2007 (12).

N. jatamansi is listed as “Critically Endangered” on 2017.1 IUCN Red List (1), and N. jatamansi DC is on the verge of extinction from over harvesting and degradation of its environment in India, Pakastan, Nepal, Tibet, China, and Yunan (33).  Unregulated root collection and loss of habitat needs to be addressed (36).  Further, The Red Data Book of Indian Plants lists 17 species, including N. jatamansi DC.  RAPD is a method used in measuring biodiversity of a species: polymorphism, and characterizes variability.  N. jatamansi  DC was collected and analyzed from India and Nepal to determine better propagation strategy to maintain diversity and conserve the plant in high demand for its medicinal properties (37).

Agarwood Oil (Aquilaria crassna and Gyrinops species)

Also called oud, agalocha, gaharu, aloeswood, and eaglewood, and kiara, Aquilaria Crassnais “Critically Endangered” on 2017.1 IUCN Red List (1), and multiple species are listed on CITES (12).  In high demand and reputed to be the most expensive wood in the world, it can be found in North Eastern India, Bhutan, South East Asia, and Thailand.  The aroma from agarwood is created when a fungus infects the tree.  Aquilaria crassna is also protected by the Vietnam government, with overarvesting causing a population reduction of over 80%  (38).  It is a very expensive essential oil and overharvesting has resulted in seven other Aquilaria species being designated as “Vulnerable” on the 2017.1 IUCN Red List (1) and all species of Aquilaria and Gyrinops were placed on the CITES Appendix II list of International Trade in Endangered Species (39).  The Indian Forest Act bans extraction and export, to reduce genetic erosion via CIMAP 1997 (11). 

Cedarwood atlas(Cedrus atlantica and many Juniperus species)

Cedarwood oils are obtained from three main species.  In America, Juniperus ashei Buch is found in Texas and Juniperus virginiana L. is found in Virginia.  In Morocco and India, there is the Cedrus species and in China, it is the Cupressus species.  It is the Cedrus species whose populations are of the most concern.  The essential oil has been marketed for being antiseptic, anticatarrhal, as an expectorant, and as a circulatory stimulant (40).  It is also used for furniture, carpentry, construction, tar making, and as an insect repellent.

Especially in Morocco, C. atlantica is on the 2017.1 IUCN Red List (1) as “Endangered” with up to a 75% decline in population between 1940 and 1982 and continuing to dwindle (41).  The Atlas Mountains of Morocco are a Mediterranean Red Alert area with 10,000 km2 of the forest disappearing from 1940 to 1982 and a 40% loss over the past three decades (40).  The World Wildlife Fund (WWF) classifies the conifer forests of North Africa, Morocco, North Tunisia, and North West Algeria as “Critically Endangered” (40).  Pest outbreaks and a more arid climate have worsened the situation along with overgrazing and fires (41).  C. deodara (Himalayan cedarwood), and C. libani of Lebanon are additional Cedrus species listed on the 2017.1 IUCN Red List (1).  Further, the 1991 – 1996 drought has rendered the area ecologically fragile and susceptible to desertification, erosion, demineralization, and dehydration (40).

Juniperus procera, Kenyan cedarwood, was listed as “Endangered” by the FAO Forestry Dept. in 1986, listed as “Endangered” in Saudi Arabia and Malawi, and listed on IUCN 2010 Red List of Threatened Species (40).  Juniperus cedrus of the Canary Islands is “Endangered” with a population of only 600 sexually mature trees and decreasing (42).  Problems for this species have included exploitation of the wood for aromatic timber, a severe fire in 2007 in the El Teide National Park, and overgrazing (42).  Poor genetic diversity needs to be addressed as part of the conservation plan, and the reintroduction of more raven and wintering ring ouzel birds could aid in the long range seed dispersal (43).  Recently, in 2000, all goats were removed to improve growth (42).  Juniperus communis subsp. Hemisphaerica was identified by the nation of Morocco as “Critically Endangered” and Juniperus thurifera was listed as “Vulnerable” (3).  Widdringtonia whytei Rendle, Mulanje Cedarwood of Tropical Africa is “Critically Endangered” on the 2017.1 IUCN Red List (1), being heavily exploited for over 200 years.  Illegal logging, fires, lack of regeneration, invasive species, and pests could cause a decline of over 809% by 2030, with wood being used to build houses and illegal cutting also being a major problem (44).

Discussion

Consumers have a moral responsibility to avoid purchasing at risk plant species.  In many cases, Fair Trade goes along with this issue, where both the plants and the poor people of an area are equally exploited by big businesses who profit highly from the sales of rare essential oils in danger of extinction.  The quickest way to look up a species status is at www.iucnredlist.org, however a species may be overharvested before making it onto the IUCN’s list.  Also do a query in Google Scholar of “plant species name” and “threatened” or “endangered” to find additional scholarly status updates, often written by local experts.  In doing research, the author has noticed multiple essential oil suppliers selling listed endangered species.  In this instance, it is suggested to call the company and discuss the latest status of the species and how they get their supply before purchasing. 

The use of alternative essential oils with similar healing properties can be considered as a way to avoid endangered and threatened species.  Myrrh comes from the same plant family as frankincense: Burseraceae, and both species are small trees growing in dry climates.  The resin extracted from both frankincense and myrrh consists mainly of terpene hydrocarbons along with sesquiterpenes (45).  Both oils can be used for skin healing, immunity strength, and as a decongestant, and have been used as a spiritual incense since Biblical times.  Coriander Seed (Cilantro) from Coriandrum sativum may be a good replacement for rosewood.  Both are very high in linalool and have a sweet, spicey woody scent. 

As it relates to sandalwood, it seems easiest to recommend avoiding any varieties coming from India, Hawaii, Vanuatu, and New Caledonia unless the educated consumer investigates their source.  Alternative species from Australia include Eucaria spicata, Fusanus spicatus R. Brown, and S. cygnorum.  Brachyleana hitchensii, also called Muhuhu, may be a viable source out of Kenya and Amyris balsamifera, also called West Indian sandalwood, comes from Haiti.  Some essential oil companies suggest Ho wood oil (Cinnamomum camphora) as an alternative to Indian sandalwood, but this tree is also in danger (46).  Agarwood is an endangered tree whose resin is also highly prized.  Its smell is often described as sandalwood like, and the species listed above may be viable replacements.  With cedarwood, there are species across the world and the Moroccan variety seems to be in the most jeopardy, while in Texas, Juniperus ashei is in abundance.

Honeysuckle is in the same valerian family as spikenard, so it may be a likely alternative, but it is very costly to extract essential oil from honeysuckle flowers.  An idea would be to make a honeysuckle infused oil; however the following recipe involves the flowers and not the roots, as in spikenard.  Pick the honeysuckle flowers and allow them to dry for a few hours, but not too much longer as these very delicate flowers may wilt and lose their smell.  Put the same quantity of flowers to base oil in a glass jar and set out in the sun each day for two weeks, bringing inside in the evening.  After two weeks, strain the herbs out of the oil using several layers of muslin cloth.  It may be necessary to then re-infuse the strained oil with a fresh picking of more lightly dried honeysuckle in the same method for two more weeks to strengthen the scent.  The infused oil can be preserved by adding benzoin.  Valerian root may be another alternative to spikenard, however, as indicated in the appendix of this paper, it has multiple species on the IUCN Red List (1).

Conclusion

Frankincense, rosewood, sandalwood, spikenard, agarwood, and cedarwood atlas all make amazing essential oils, but not worth purchasing at the cost of species survival.  Research has shown stories of overharvesting, human exploitation, and lost habitat that has cost these plants dearly.

• Frankincense resin of the Horn of Africa is fraught with corruption and exploitation.
• Rosewood has been stripped in Brazil and has spread to Madagascar.
• Sandalwood, with a valuable history to the economy of India, may be overprotected by the government to the point that it discourages farmer cultivation.  Multiple species from Australia to Hawaii have gone extinct or are in serious danger.
• Spikenard export has been banned, resulting in a heavily adultered essential oil.
• Agarwood has a threatened genetic diversity, with a lack of variation affecting the species.
• Cedarwood atlas has seen its conifer forest habitat shrink drastically.

The solution to saving these plants can start with the consumer.  Stopping the purchase sends the message to the supplier that no oil is worth the cost of losing species.

December, 2019 Updated: Click here for more information about threatened essential oil species:  Aroma Apothecary Healing Arts Academy Blog Article

Appendix: Additional Essential Oil Species of Concern

References

1  IUCN Redlist (2017).  Retrieved from www.iucnredlist.org.  Retrieved in 2017.

2  Thulin, M.  (1998). Boswellia sacra.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7/10/15.  Retrieved from www.iucnredlist.org

3  Garzuglia, M. (2006). Threatened, endangered and vulnerable tree species: a comparison between FRA 2005 and IUCN red list. FAO. Forestry Department, working paper, 108.

4  Miller, A.  (2004). Boswellia ameero.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-10-15.  Retrieved from www.iucnredlist.org

5  Saha, D., Ved, D., Ravikumar, K. & Haridasan, K. 2015. Boswellia ovalifoliolata. The IUCN Red List of Threatened Species 2015: e.T50126567A50131280. http://dx.doi.org/10.2305/IUCN.UK.2015-2.RLTS.T50126567A50131280.en. Downloaded on 27 June 2017.

6  World Conservation Monitoring Centre. 1998. Boswellia ogadensis. The IUCN Red List of Threatened Species 1998: e.T34385A9857791. http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T34385A9857791.en. Downloaded on 27 June 2017.

7  DeCarlo, A., & Ali, S. H. (2014).  Sustainable Sourcing of Phytochemicals as a Development Tool: The Case of Somaliland’s Frankincense Industry.  University of Vermont.

8  Efferth, T., & Greten, H. J. (2011). Anti-inflammatory and anti-cancer activity of boswellic acids from frankincense (Boswellia serrata Roxb. et Colebr, B. carterii Birdw.). In Forum on Immunopathological Diseases and Therapeutics (Vol. 2, No. 4). Begel House Inc.

9  Frank, M. B., Yang, Q., Osban, J., Azzarello, J. T., Saban, M. R., Saban, R., & Lin, H. K. (2009). Frankincense oil derived from Boswellia carteri induces tumor cell specific cytotoxicity. BMC Complementary and Alternative Medicine, 9(1), 6.

10  Farah, A. Y. (1994). The milk of the Boswellia forests: frankincense production among the pastoral Somali. EPOS, Environmental Policy and Society.

11  Burfield, T.  (2010).  Cropwatch’s Rosewood Biblio (Aniba rosaedora Ducke) together with other related & unrelated Aniba spp.  Retrieved on 7/6/15.  Retrieved from www.cropwatch.org/Rosewood%20Biblio%201.07.pdf

12  CITES (2017).  Retrieved from www.cites.org.  Retrieved in 2017.

13  Varty, N.  (1998). Aniba rosodora.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-10-15.  Retrieved from www.iucnredlist.org

14  Martins, E. M., Lamont, R. W., Martinelli, G., Lira-Medeiros, C. F., Quinet, A., & Shapcott, A. (2015). Genetic diversity and population genetic structure in three threatened Ocotea species (Lauraceae) from Brazil’s Atlantic Rainforest and implications for their conservation. Conservation Genetics, 16(1), 1-14.

15  Singh, S. (2013). The Socio-economic context of illegal logging and trade of rosewood along the Cambodian-Lao border.

16  Munhoz, C. A., Silva, J. V. D., & Marques, M. (2014). Demography of the endangered tree species Ocotea porosa (Lauraceae) along a gradient of forest disturbance in southern Brazil. Acta Botanica Brasilica, 28(4), 617-623.

17  Barrett, M. A., Brown, J. L., Morikawa, M. K., Labat, J. N., & Yoder, A. D. (2010). CITES designation for endangered rosewood in Madagascar. Science, 328(5982), 1109-1110.

18  Schuurman, D., & Lowry II, P. P. (2009). The Madagascar rosewood massacre. Madagascar Conservation & Development, 4(2).

19  Patel, E. R. (2007). Logging of rare rosewood and palisandre (Dalbergia spp.) within Marojejy National Park, Madagascar. Madagascar Conservation & Development, 2(1).

20  Soundararajan, V., Ravi Kumar, G., & Murugesan, K. (2015). Trade Scenario of Sandalwood and its valued oil. International Journal of Novel Research in Marketing Management and Economics, 2(3), 52-59.

21  Rao, M. S., Ravikumar, G., Triveni, P. R., Rajan, V. S., & Nautiyal, S. (2016). Analysis of policies in sustaining sandalwood resources in India. In Climate Change Challenge (3C) and Social-Economic-Ecological Interface-Building (pp. 327-346). Springer International Publishing.

22  Indrioko, S., & Ratnaningrum, Y. W. (2015). Habitat loss caused clonality, genetic diversity reduction and reproductive failure in Santalum album (Santalaceae), an endangered endemic species of Indonesia. Procedia Environmental Sciences, 28, 657-664.

23  Rashkow, E. D. (2014). Perfumed the axe that laid it low: The endangerment of sandalwood in southern India. Indian Economic & Social History Review, 51(1), 41-70.

24  Rohadi, D., Setyawati, T., Maryani, R., Riwukaho, M., Gilmour, D., Boroh, P., & Lukas, E. (2012). Strategies for Sustaining Sandalwood Resources in East Nusa Tenggara, Indonesia. IUFRO World Series Vol. 30, 69.

25  Jinfeng, Z., & Sinha, A. (2012).  Workshop Programme.  IUFRO World Series Vol 30, 123.

26  Logan, L., & Cole, G. (2001). New Caledonia. Lonely Planet.

27  United Plant Savers. (2015).  Retrieved in 2015.  Retrieved from www.unitedplantsavers.org

28  Pejhanmehr, M. & Adams, J. 2016. Santalum freycinetianum. The IUCN Red List of Threatened Species 2016: e.T62929A95817407. http://dx.doi.org/10.2305/IUCN.UK.2016-2.RLTS.T62929A95817407.en. Downloaded on 27 June 2017.

29  Butaud, J. F., Rives, F., Verhaegen, D., & Bouvet, J. M. (2005). Phylogeography of Eastern Polynesian sandalwood (Santalum insulare), an endangered tree species from the Pacific: a study based on chloroplast microsatellites. Journal of Biogeography, 32(10), 1763-74.

30  Eddowes, P.  (1998). Santalum macgregorii.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-10-2015.  Retrieved from www.iucnredlist.org

31  Huish, R. D., Faka’osi, T., Likiafu, H., Mateboto, J., & Huish, K. H. (2015). Distribution, population structure, and management of a rare sandalwood (Santalum yasi, Santalaceae) in Fiji and Tonga. Pacific Conservation Biology, 21(1), 27-37.

32  CAMP Workshops on Medicinal Plants, India. (1998).  Pterocarpus santalinus.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-24-15.  Retrieved from www.iucnredlist.org

33  Gupta, R. K., Disket, J., & Mann, S. (2012). A Review on Spikenard (Nardostachysjatamansi DC.)-An ‘Endangered’Essential Herb of India. International Journal of Pharmaceutical Chemistry, 2(2), 52-60.

34  Singh, U. M., Gupta, V., Rao, V. P., Sengar, R. S., & Yadav, M. K. (2013). A review on biological activities and conservation of endangered medicinal herb Nardostachys jatamansi. Int. J. Med. Arom. Plants, 3(1), 113-124.

35  Keshari, D. S., Bishnupriya, M., Panda, P. K., & Arun, J. B. (2015). A study of various market samples of spikenard. Global Journal of Research on Medicinal Plants & Indigenous Medicine, 4(3), 46.

36  Ved, D., Saha, D., Ravikumar, K. & Haridasan, K.  (2015). Hydnocarpus pentandrus.  The IUCN Red List of Threatened Sopecies.  Version 2015.2.  Retrieved on 7/22/15.  Retrieved from www. Iucnredlist.org

37  Singh, U. M., Yadav, D., Tripathi, M. K., Kumar, A., & Yadav, M. K. (2013). Genetic diversity analysis of Nardostachys jatamansi DC, an endangered medicinal plant of Central Himalaya, using random amplified polymorphic DNA (RAPD) markers. African Journal of Biotechnology, 12(20), 2816-2821.

38  Nghia, N.H. 1998. Aquilaria crassna. The IUCN Red List of Threatened Species 1998: e.T32814A9731504. http://dx.doi.org/10.2305/IUCN.UK.1998.RLTS.T32814A9731504.en. Downloaded on 27 June 2017.

39  Buapech, S, Changtragoon, S. and Eiadthong, W.  (2012). Genetic diversity of Aquilaria crassna (Thymelaeaceae) in Thailand using microsatellite markers.  IUAFO World Series 2012.

40  Burfield, T.  (2004). A short note on the ecological status of cedarwood atlas: Cedrus atlantica (Endl.) Carr.  Retrieved on 7/6/15.  Retrieved from www.cropwatch.org/cedarwood.htm

41  Thomas, P.  (2013).  Cedrus atlantica.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrievbed on 7-10-15., Retrieved from www.iucnredlist.org

42  Rumeu Ruiz, B, de Sequeira, M, Elliot, M & Gardner, M. 2011. Juniperus cedrus. The IUCN Red List of Threatened Species 2011: e.T30327A101032366. http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T30327A101032366.en. Downloaded on 27 June 2017.

43  Rumeu, B., Vargas, P., Jaén-Molina, R., Nogales, M., & Caujapé-Castells, J. (2014). Phylogeography and genetic structure of the threatened Canarian Juniperus cedrus (Cupressaceae). Botanical journal of the Linnean Society, 175(3), 376-394.

44  Farjon, A.  (2013).  Widdringtonia whytei.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-10-15.  Retrieved from www.iucnredlist.org. 

45  Schnaubelt, K.  (1995). Advanced aromatherapy.  The science of essential oil therapy.  Healing Arts Press.  Rochester, VT.

46  Linghai, Z., Huiming, L., Qian, Z., Yanling, C., & Boxiang, H. (2012). Camphor Tree Resources and Utilization. IUFRO World Series Vol. 30, 59.

47  El Bahloul, Y., Dauchot, N., Machtoun, I., Gaboun, F., & Van Cutsem, P. (2014). Development and characterization of microsatellite loci for the Moroccan endemic endangered species Argania spinosa (Sapotaceae). Applications in plant sciences, 2(4).

48  Williams, S. (2005). Socio-economic aspects of the sustainable harvesting of buchu (Agathosma betulina) with particular emphasis on the Elandskloof community (Doctoral dissertation, University of the Western Cape).

49  Lokesh, G. B., & Chandrakanth, M. G. Conservation of Endangered Medicinal plant: Management of Sewage water in urban fringes and water logged marshy lands in India.

50  Ved, D., Saha, D., Ravikumar, K., & Haridasan, K.  (2015).  Valeriana leschenaultia.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7/24/15.  Retrieved from www.iucnredlist.org

51  Singh, R., Gangwar, S. P., Singh, D., Singh, R., Pandey, R., & Kalra, A. (2011). Medicinal plant coleus forskohlii briq: disease and management. Med Plants, 3(1), 1-7.

52  Knees, S. & Gardner, M.  (2011).  Abies nordmanniana ssp. Equi-trojani.  The IUCN Red List of Threatened Species.  Version 2015.2.

53  Behera, M. & Raina, R. (2012).  Gentiana kurroo Royl – A critically endangered bitter herb.  International Journal of Medicinal and Aromatic Plants, 2(1), 22-9.

54  Zhang, D., & Christian, T.  (2013). Chamaecyparis formosensis.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-22-15.  Retrieved from www.iucnredlist.org

55  Shabir, P. A., Nawchoo, I. A., & Wani, A. A. (2010). Development of vegetative and sexual multiplication protocol for commercialization of Inula racemosa Hook. f.–A critically endangered medicinal plant of NW Himalaya. Nat. Sci, 8(10).

56  Preetha, T. S., HemanthaKumar, A. S., & Krishnan, P. N. (2013). Shoot tip cryopreservation by vitrification in Kaempferia galanga L. an endangered, overexploited medicinal plant in Tropical Asia. IOSR Journal of Pharmacy and Biological Sciences, 8, 19-23.

57  Giri, D., & Tamta, S. (2012). Effect of pre-sowing treatments on seed germination in Hedychium spicatum: An important vulnerable medicinal plant of Indian Himalayan region. Scientific Research and Essays, 7(19), 1835-1839.

58  Thomas, P.  (2010). Neocallitropsis pancheri.  The IUCN Red List of Threatened Species. Version 2015.2.  Retrieved on 7/24/15.  Retrieved from www.iucnredlist.org

59  Yong Eui, C., ChulWoo, K., & JaeSeon, Y. (2012). Conservation and Restoration Strategy for Wild Forest Ginseng (Panax ginseng CA Meyer). IUFRO World Series Vol. 30, 79.

60  Bazlichuk, N.  (2012). Norway’s first red list for ecosystems.  Science Nordic.  11/29/2012.

61  Thomas, P. & Yang, Y.  (2013). Fokienia hodginsii.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7.24.15.  Retrieved from www.iucnredlist.org

62  Saha, D., Ved, D., Ravikumar, K., & Haridasan, K.  (2015). Saussurea costus.  The IUCN Red List of Threatened Species.  Version 2015.2.  Retrieved on 7-22-15.  Retrieved from www.iucnredlist.org

63  Yooyuen, R., Duangjai, S., & Changtragoon, S. (2012). Chloroplast DNA Variation of Dalbergia cochinchinensis Pierre in Thailand and Laos. IUFRO World Series Vol. 30, 84.

64  Rimbawanto, A. (2012). Conservation of Genetic Resources of Sandalwood (Santalum album L. var. album) in Timor Islands. IUFRO World Series Vol. 30, 36.