Eucalyptus


Eucalyptus is a genus of flowering plants with over 500 species and is a member of the Myrtaceae family. (Tudge 2007) Eucalyptus is native to Australia where it is the main source of food for koalas. Many times, species are referred to as 'the gum tree' or 'blue gum' referring to the tree's sap. Eucalyptus' therapeutic use was part of traditional Chinese medicine. Eucalyptus is still a popular herbal remedy. Herbal remedies are often made with oil from Eucalyptus trees and dried leaves from the tree. (Anonymous 2011)


Eucalyptis Globulus, among others...



Eucalyptus globulus
Eucalyptus globulus
Eucalyptus globulus AKA 'Australian fever gum', is a very common species of Eucalyptus. The tree pictured to the left illustrates the shear size of the tree- some Eucalyptus trees can grow up to 230 feet. (Anonymous 2011) Notice the eroding bark on the tree. Eucalyptus has so many different types of bark, often times species are group by bark characteristics:

Stingybark- long fibers that can easily be pulled off. Usually thick with a spongy texture.
Ironbark- hard, rough deep and furrowed. Soaked with dried sino (sap) which gives it a red color.
Tessellated- bark is broken up into many distinct flakes.
Box- has short fibers. Shows some tesselation.
Ribbon- bark coming off in long, thin pieces, but still loosely attached in places. Long ribbons or twisted curls. (Audubon Society 1980)

On the right is a picture of a Eucalyptus leaf. If you click on the picture, you can get a better look at the leaf and its flowering buds.
Many of the mature Eucalyptus leaves take the shape shown on the right. This leaf has long, narrow shape, and many sources describe the texture as a leathery feel.
external image 220px-Apple_box_leaf_and_flowerbuds.jpg
The bottom left is a flower and fruits of a species called Eucalyptus melliodora. As you can see, the flower contains many white stamens in cap called the operculum. 'Eucalyptus' is derived from Greek: (eu) "well" (kalyptos) "coverered." The name directly references the operculum of the flower. (Gledhill 2008)


Eucalyptus melliodora
Eucalyptus melliodora


Plant Family and Relatives


Kingdom:
Plantae
(unranked):
Angiosperms
(unranked):
Eudicots
(unranked):
Rosids
Order:
Myrtales
Family:
Myrtaceae
Subfamily:
Myrtoideae
Tribe:
Eucalypteae
Genus:
Eucalyptus
Callistemon inflorescence
Callistemon inflorescence

This scientific classification, from wikipedia, provides a more in-depth look at Eucalyptus. Many of the catagories have links for more information. "The eucalypts are within the plant family Myrtaceae and can number among their relatives such well known Australian genera as Callistemon (bottlebrushes), Melaleuca (paperbarks), Leptospermum (tea trees) and Syncarpia (turpentine)." (Anonymous 2009) In fact all the Myrtaceae family members are generally native to Australia, I have found. Including the Callistemon on the right. These plants are shrubs similar to some Eucalypt species. One strong trait resemblance they share is illustrated by the flowering of the Callistemon- the flowers' stamen and operculum's. Each genera has plants that have identical, or similar flowers. Both have no or few petals, but an abundance of stamen. Both flowers are encompassed by a dominating operculum.
The term "eucalypts" was quoted. "Euclypts" refers to Eucalyptus, Corymbia, and Angophora because all are so closely related. To the bottom left is a photo of a Corymbia plant flowering. Again the stamen and operculum stand out, "In Eucalyptus and Corymbia the petals and stamens are fused into a cap called an operculum which covers the flowers at the bud stage." (Amonymous 2009) However Angophora are distinguished from Eucalytus because they have no operculum and the flowers develop with petals. (Anonymous 2009) Another differential trait is the seeds produced. Eucalyptus have a smooth shell while Corymbia seeds have sharp ribs. According to wikipedia, genetic research has been published linking Angophora closer to Ecalyptus than Corymbia.
Corymbia
Corymbia


Melaleuca armillaris
Melaleuca armillaris

Another family member that shares characteristics of Eucalyptus is Melaleuca. Melalueca is medium-sized tree known for its paper-like bark. What it is really known for is commercial use. The oil is used for medicinal purposes as an antibiotic or anti-fungal. Australians will often make tea out of the leaves. Melaleuca is called "the tea tree" often because of its success at relieving headaches and pain. Eucalyptus is similarly used for medicinal purposes such as coughs, colds, and gum disease. (Anonymous 2011) The picture on the right shows the plant's leaves. Unlike Eucalyptus the flowers come with small petals. Flower colors of the leaves vary and the fruit is a small capsule with seeds. Amongst all Myrtaceae is the characteristic of oil grands. (Rozefelds 1996) Every species produces a lot of oil, often sap through tree bark.


Geographic Distribution of Eucalyptus





Eucalyptus Global Cultivation 2008
Eucalyptus Global Cultivation 2008






Eucalyptus is native to Australia, which included Tasmania at the time. As you can see from the map, eucalyptus grows prolifically in other parts of the world. The map shows hectares (measurement of forestry) where eucalyptus plants grow. South America, India, China, Africa and other parts of Asia has seen an abundance of cultivation. Eucalyptus can flourish in a tropical environment because of its ability to retain water and live off very little of it. Although it may not be visible on the map, eucalyptus species have also flourished in California and Hawaii.




Uses and Efficacy


Eucalyptus has always been a versatile herbal remedy, "the oil was used in traditional Aboriginal medicines to heal wounds and fungal infections. Teas made of eucalyptus leaves were also used to reduce fevers. Eucalyptus soon spread to other traditional medicine systems, including Chinese, Indian, Greek and European. In 19th-century England, eucalyptus oil was used in hospitals to clean urinary catheters. Laboratory studies later showed that eucalyptus oil contains substances that kill bacteria. It may also kill some viruses and fungi." (Anonymous 2011) Eucalyptus is still used medicinally as it is a key ingredient in certain medicines.

Medicinal Uses
  • Cough and cold- Eucalyptus can treat cough and colds and it is found in many lozenges and cough medicines. Ointments containing the plant may also be used by being applied to the nose and chest. Herbalists recommend tea made out of fresh leaves and then gargling it to soothe throats and treat bronchitis. Eucalyptus oil helps loosen phlegm, so inhaling eucalyptus steam may help treat bronchitis, coughs and flu. (Anonymous 2011) Some known products: Vicks VapoRub.
  • Plaque and gum disease- Eucalyptus oil is rich in cineole, an antiseptic that kills bacteria that can cause bad breath. Eucalyptus is used in some antiseptic mouthwashes, along with other oils. The mouthwashes have been shown to prevent plaque and gingivitis. (Anonymous 2011) Some known products: Listerine
  • Other Uses- Applied to skin, oil has been used to treat arthritis and sores. It may ease muscle and joint pain.
    Now Foods Eucalyptus Oil (Certified Organic) Certified Organic Eucal
    Now Foods Eucalyptus Oil (Certified Organic) Certified Organic Eucal
  • For more info from completely unofficial herbal guides: Eucalyptus guide
Recipes for Eucalyptus

Repellent
  • Eucalyptus is an active ingredient in insect repellent. One study from Maryland Medical School proved oil successfully repelled ticks.

Commercial Products
Eucalyptus' are one of the world's biggest tree and many species have uniquely valuable wood. Here are some traditional commercial uses in Australia:
  • Building
  • Furniture
  • Paper
  • Wood Chips (Anonymous 2009)
Eucalyptus industry
Eucalyptus industry

The picture on the right is eucalyptus globulus being used as a commercial product. Much to the chagrin of botanists and
others, eucalyptus trees are being treated as a commodity, rather than a plant.


Active Compounds
Eucalyptus leaves contain tannins, which are believed to help reduce inflammation; flavonoids, plant-based antioxidants; and volatiles oils. (Anonymous 2011) Cineole is a very active compound as well.



Side Effects of Use
Almost every resources states that when using eucalyptus (medicinally), know that herbs can trigger sides effects and tend to interact with other herbs or medicines. Essentially, one should consult a health care provider before using it. If one is on medication there may be an interaction that only doctor's know about. According to multiple resources including Maryland Medical Center, Eucalyptus should not be taken with any medication containing 5-Fluorouracil (5-FU). Also medline plus highly warned against any medications that changed by the liver. A lot of medications are broken down and changed by the liver. Some examples are accutane, lithium, zyprexa. Multiple resources also warned about taking Eucalyptus orally. Since the oil is toxic it should properly be diluted before being ingested or inhaled.

Effectiveness
According to medline plus , although Eucalyptus is used medicinally for many purposes, there is not enough scientific evidence to prove that they are effective. There are certain pieces of positive evidence: multiple resources including medline found that a chemical in eucalyptus oil breaks down phlegm. In fact the University of Maryland Medical Center backed up its findings of eucalyptus being effective as a supplement. While medline also described some of these uses, the key concept is the lack of scientific evidence. This may simply mean that scientists just haven't taken the time to study eucalyptus within each medicinal product. Another factor may be the lack of longevity. This means researched hasn't been conducted over a long enough span to determine if eucalyptus is effective. However just because science cannot necessarily answer, people can use history and shared knowledge to know that eucalyptus can be effective. Even if it serves as a placebo like many herbal medicines, that may work as well.


References



Anonymous. (2009) Eucalyptus, Corymbia, and Angophora. Austrialia Native Plant Society. Retrieved from
http://anpsa.org.au/eucal1a.html

Anonymous. (2011) Eucalyptus. University of Maryland Medical Center. Retrieved from
http://www.umm.edu/altmed/articles/eucalyptus-000241.htm

"Eucalyptus Cultivated Map 2008" <http://git-forestry-blog.blogspot.com/2008/09/eucalyptus-global-map-2008-cultivated.html

Gledhill, D. (2008) The Names of Plants (4 ed.). Cambridge University Press. P 158.

"Medline" (2011) http://www.nlm.nih.gov/medlineplus/druginfo/natural/700.html


National Audubon Society. (1980) National Audubon Society Field Guide to North American Trees--E: Eastern Region, Chanticleer
Press Ed (Knopf)

Rozefelds, A.C. (1996) Eucalyptus Phylogeny and History: A brief summary. Tasforests Vol. 8. Retrieved from:
http://www.forestrytas.com.au/assets/0000/0377/vol_8_pages15-26.pdf


Tudge, Colin. (2007) The Tree: A Natural History of What Trees Are, How They Live, and Why They Matter, Reprint (Three
Rivers Press).