Cinnamomum camphora: Camphor Tree

Common English Names: Camphor Tree, Camphor Laurel

Japanese Name (Katakana): クスノキ　

Japanese Name (Kanji): 楠

There are few tree species whose global reputation varies as remarkably as Cinnamomum camphora (クスノキ, “Kusunoki”), the camphor tree. A giant of the broadleaf forests of Japan, it grows between 15 - 30 meters tall, though some in China have reached heights of 50 meters. It cuts a massive and intriguing figure, with thick and contorted branches that carry aromatic leaves that smell of camphor. Aside from its impressive appearance, Cinnamomum camphora also has long cultural and historical ties with Japanese religious traditions as a tree of spiritual and symbolic importance. The species is among some of the oldest and largest living trees in the country, many of which are protected by the government. It has medicinal properties that have long associated the tree with healing and protection, even after the use of camphor to treat illness became less common. In its non-native range, however, it has a less-than-divine reputation as a persistent invasive species and noxious weed where it quickly colonizes disturbed sites and can effectively displace native species. Despite the apparent duality, both of these reputations are informed by the same traits that make Cinnamomum camphora such a long-lasting and resilient ecological competitor.

Cinnamomum camphora’s Japanese name hints at its cultural and historical importance in Japan and its myriad of practical uses. One theory proposes that クスノキ (“Kusunoki”) originates from the word クスリノキ “Kusuri-no-ki,” which literally means “tree of medicine.” The medicine in question is camphor oil, which is derived from the wood and roots of the tree and has pain-relieving and anti-inflammatory properties. The word クスノキ (“Kusunoki”) may also derive from クスシキ (“Kusushi-ki”), a word no longer used in modern Japanese that means “mysterious” and is itself the origin of the word for medicine, クスリ (“Kusuri”). In addition to “mysterious tree,” クスシキ (“Kusushi-ki”) has another meaning: “stinky tree.” Known for its strong medicinal odor, camphor can be smelled from the bark of Cinnamomum camphora as well as from its crushed leaves.

In addition to its medicinal and aromatic qualities, camphor oil and wood also serve as effective insect repellants. While that was probably a most welcome relief for those living in the damp, warm climates Cinnamomum camphora prefers, the wood’s insecticidal properties also made it a useful material for construction. This was especially true in the production of religious statues in Shinto shrines and Buddhist temples, where large Cinnamomum camphora trees were often already present. In fact, many of the largest and oldest examples of Cinnamomum camphora in Japan are located in or near temples and shrines and are protected and maintained as prefectural or national monuments. One tree, determined to be at least 1,500 years old, can be found at Kamo-Hachiman Shrine in Aira, Kagoshima. It is currently one of the largest living trees in Japan, with a height of 30 meters and a trunk circumference of 24.2 meters. What’s more, historical records indicate that the tree pre-dates the construction of the shrine, and was already quite sizable when the shrine was being built in the year 1123.

In addition to their presence near shrines and temples and their variety of practical uses, in some places Cinnamomum camphora trees were assigned great spiritual significance. According to traditional Japanese folklore and Shinto traditions, trees that are particularly massive and older than 100 years can be home to tree spirits called kodama. Though the presence of kodama is sometimes associated with providing protection and healing, grave misfortune is said to follow those who cut down trees in which kodama reside. Such trees are considered sacred, and are often marked near shrines with a straw rope called a shimenawa. Many of the massive Cinnamomum camphora that remain alive today have associations with this tradition.

Such spiritual associations with trees are also present in many Buddhist temples in Japan as the result of a long and complex history of exchange, combination, and syncretism with Shinto beliefs and practices. Koyasu-kannon (子安観音), a small Buddhist temple in Sasebo, Nagasaki, is home to a 400-500 year old Cinnamomum camphora tree with a record of such religious significance, perhaps also rooted in the tree’s medicinal applications. Local legends recount how a devastating plague occurred several hundred years ago after the tree was almost entirely chopped down. To eradicate the plague, those in the nearby village conducted a ritual to appease the enraged tree entity and afterwards regarded it as a tree that could fend off bad fortune and disease if it continued to be properly revered. Since then, the tree has regrown, with seven separate trunks branching off from the main trunk where it had previously been chopped down. The name of the village where the tree is located is called “Arifuku,” which translates literally to “luck is present” in reference to the guardianship of that tree. The tree was designated as a natural monument by the prefecture in 1970.

Though the cultural and religious landscape of Japan has changed significantly in the past several hundred years, camphor trees have continued to have cultural and symbolic significance in the 20th and 21st century. Cinnamomum camphora were among the trees that survived the atomic bombings of Nagasaki and Hiroshima in August 1945 (called Hibakujumoku or “survivor trees”). Among these were three camphor trees in Shirakami Shrine in Hiroshima that survived despite being less than 500 meters from the hypocenter and everybody in the shrine perishing at the time of the blast. Though the above-ground position of the trees had burned, the trees eventually regrew from their surviving roots. Following the bombings, Cinnamomum camphora was among the quickest tree species to regenerate and again served as an important example of resilence, recovery, healing, and vitality.

The idea of Cinnamomum camphora as a tree of spiritual significance that provides protection or comfort persists in some present day cultural depictions. Most notably, the tree makes several memorable appearances in the movies of animator and filmmaker Hayao Miyazaki, including My Neighbor Totoro. In the film, forest spirits called “totoros” live in a massive camphor tree, which is marked with a small Shinto shrine and shimenawa. The tree serves as a symbol of comfort and protection from disease as two young girls navigate the complexity of their mother’s illness. Given Cinnamomum camphora’s medicinal associations as well as its ties to Shinto and forest spirits, Miyazaki would have been hard pressed to find a more appropriate tree to serve this purpose.

While Cinnamomum camphora can still be widely found in the hillside and mountainside forests of Japan today, this species is also commonly planted in parks and along streets. Other countries in its native range include China, Vietnam, North and South Korea, and Taiwan where it prefers a warm, subtropical climate with plenty of rain and mild winters. It possesses an extensive history of cultivation both within and outside of its native range. In China, the tree is still grown for medicinal and insecticidal use; in Nepal and India, the wood is cultivated for use in cremation. Beginning in the 1800s, the species was introduced to a wide variety of countries that were once European colonies and to places along European trade routes, including Australia, Mauritius, the United States, Egypt, Tanzania, Kenya, Argentina, and more.

While the species was often introduced with the intention of ornamental cultivation or producing camphor oil, in subtropical areas the species often quickly became naturalized. Today, it is found on every continent (except Antarctica) and, outside of its home range, is often considered a persistent invasive species and noxious weed. Cinnamomum camphora is a fierce ecological competitor that colonizes recently disturbed or neglected sites. Growing quickly to develop large canopies and massive root systems, they can effectively outcompete native species for light and soil resources. In addition, the tree may release biochemicals that impair the growth of other plant species around it through a phenomenon called allelopathy. Cinnamomum camphora trees are also prolific reproducers. Mature trees can produce upwards of 100,000 fruits that are popular with and easily dispersed by a variety of bird species. This means new rows of Cinnamomum camphora can pop up quickly along riverbanks, roadsides, fence lines, and under power lines where birds perch and excrete seeds. As a result, controlling the expansion of Cinnamomum camphora in its non-native range often proves difficult and expensive.

Whether as a noxious weed or as a divine tree, Cinnamomum camphora is a persistent and resilient species with a fascinating history and cultural identity. Though its ecological competitiveness can cause serious disruption outside of its native range, that is also part of what has ensured its continued (and monumental) existence in the forests, temples, and shrines of Japan as symbols of healing, protection, and regeneration. With such a varying reputation that ranges from the invasive to the sacred, Cinnamomum camphora serves as yet another reminder of how attitudes and the perceptions of a species can be deeply rooted in ecology.

ID Information

Leaves: The leaves are evergreen, simple, hairless, dark green in color, have shiny upper surfaces with paler undersides, and alternate along the branch. Leaves can vary between 4.5 - 11 cm long and 3 - 6 cm wide. Its stalks (or petioles) are usually 2 - 4 cm long. New leaves may have shades of pink or red, though the color may vary slightly depending on the environment, age of the tree, and the time of year. The edges (or margins) are smooth and noticeably wavy. Leaves will give off the distinct smell of camphor if cut or crushed. Some say the smell is very medicinal, or smells like menthol. Some insects like the Common Bluebottle (Graphium sarpedon, アオスジアゲハ) feed on the leaf.

On each leaf, three veins are especially apparent (the center vein plus two side veins). Where the two side veins meet the center vein there will often be two little bumps visible. These are small chambers or glands called domatia where mites nest. Often, the tree has a mutualistic relationship with some species of mites that fend off harmful insects and other arthropods.

Bark: Mature bark is rough, light brown or gray in color, and vertically fissured (or split). When younger, the bark may appear greenish and smooth.

Flowers and Fruit: Flowers appear from April - June, are small (1 - 2 mm wide), white-yellow or white-green, and hermaphroditic (have both male and female reproductive parts). The flowers grow from the ends of branches in clusters 5 - 7.5 cm long and are pollinated by dipteran flies.

Fruit is present from October - November. The fruit is a drupe, which consists of a fleshy layer covering a hardened seed (similar to a cherry, which is also a drupe). It is .5 - 1 cm wide, black when ripened, and attractive to some bird species. Fruits, along with the leaves and roots, can be very toxic to humans.

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References:

Brazil, Mark. “A Camphor By Any Other Name.” The Japan Times, 1 Aug. 2002, www.japantimes.co.jp/life/2002/08/01/environment/a-camphor-by-any-other-name/.

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“Cinnamomum Camphora (Camphor Laurel).” Invasive Species Compendium, Centre for Agriculture and Bioscience International (CABI), 21 Nov. 2019, www.cabi.org/isc/datasheet/13519.

Foster, Michael Dylan. The book of yokai: Mysterious creatures of Japanese folklore. University of California Press, 2015.

Ferguson, James J., et al. “Allelopathy: How Plants Suppress Other Plants.” Electronic Data Information Source (EDIS), University of Florida Extension, Horticultural Sciences, 26 Aug. 2016, edis.ifas.ufl.edu/hs186.

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Navie, Sheldon, and Steve Adkins. “Cinnamomum Camphora (Camphor Laurel).” Edited by Agnes Lusweti et al., Keys and Fact Sheets, BioNET - East African Network for Taxonomy, Mar. 2011, keys.lucidcentral.org/keys/v3/eafrinet/weeds/key/weeds/Media/Html/Cinnamomum_camphora_(Camphor_Laurel).htm.

Nishida, Sachiko, Akiyo Naiki, and Takayoshi Nishida. "Morphological variation in leaf domatia enables coexistence of antagonistic mites in Cinnamomum camphora." Canadian Journal of Botany 83.1 (2005): 93-101.

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Field Guides Consulted:

Title: 葉っぱで見分け五感で楽しむ樹木図鑑 (Happa de miwake gokan de tanoshimu jumokuzukan)

Author: 林将之 (Hayashi Masayuki)

Publishing Date and Publisher: 2014, ナツメ社

Language: Japanese

Title: 樹皮・葉でわかる樹木図鑑 (Juhi・Hadewakaru jumokuzukan)

Author: 菱山忠三郎 (Hishiyama Chuzaburo)

Publishing Date and Publisher: 2011, 成美堂出版

Language: Japanese

Photography by Taiga Araki and Siri McGuire