Eucalyptus Tree - Eucalyptus globulus
Live Eucalyptus trees photographed at Thousand Oaks, California, USA.
 


Figure 1. Mature Eucalyptus Trees


Figure 2. Eucalyptus Bark - Ribbon Type

Eucalyptus is a diverse genus of trees which dominate the tree flora of Australia with over 700 species. Eucalypts are found in almost every part of the continent, adapted to all climatic conditions. No other continent is so characterized by a single genus of tree as is Australia by Eucalyptus. Many species are commonly called gum trees; other common names include mallee, box, ironbark, stringybark, and ash. [1]

Eucalypts are among the tallest trees in the world. Eucalyptus regnans, the Australian Mountain Ash, is the tallest of all flowering plants (Angiosperms), growing to nearly 200 meters.

Eucalyptus species are sometimes grouped by bark characteristics:
  • Stringybark - consists of long-fibers and can be pulled off in long pieces. It is usually thick with a spongy texture.
  • Ironbark - is hard, rough and deeply furrowed. It is soaked with dried kino (a sap exuded by the tree) which gives a dark red or even black color.
  • Tessellated - bark is broken up into many distinct flakes.
  • Box - has short fibers. Some also show tessellation.
  • Ribbon - this has the bark coming off in long thin pieces but still loosely attached in places. They can be long ribbons, firmer strips or twisted curls. [2]
 

The leaves are leathery in texture, hang obliquely or vertically, and are studded with glands containing a fragrant volatile oil. The flowers in bud are covered with a cup-like membrane (hence the name of the genus, from the Greek eucalyptos, well-covered), which is thrown off as a lid when the flower expands. The fruit is surrounded by a woody, cup-shaped receptacle and contains numerous minute seeds.

Medicinal Action and Uses---Stimulant, antiseptic, aromatic.
The medicinal Eucalyptus Oil is probably the most powerful antiseptic of its class, especially when it is old, as ozone is formed in it on exposure to the air. It has decided disinfectant action, destroying the lower forms of life. Internally, it has the typical actions of a volatile oil in a marked degree.
 
References
  1. Colin Tudge, The Tree: A Natural History of What Trees Are, How They Live, and Why They Matter, Reprint (Three Rivers Press, 2007).
  2. NATIONAL AUDUBON SOCIETY, National Audubon Society Field Guide to North American Trees--E: Eastern Region, Chanticleer Press Ed (Knopf, 1980).