11 Oct

Tree of the month: Eucalyptus

This month we look at the fragrant Eucalyptus Tree! With its striking blue-grey leaves and medicinal properties, both humans and koalas alike adore this fast-growing tree…

A staple in any elegant flower arrangement or wedding bouquet, branches of Eucalyptus have become just as popular as Roses and Peonies once were among florists and wedding stylists. However, what about the trees that these beautiful silvery sprigs come from?  

There are more than 660 species of Eucalyptus trees and shrubs, which are all part of the very extensive Myrtle (Myrtaceae) family. Heralding from Australia, Tasmania, and other nearby islands, they are commonly referred to as stringybark trees or gum trees because of their thick and sticky sap, which is not technically a gum but is a tannin-like substance. About three-quarters of the forests across Australia consist of Eucalyptus and they are, of course, the main diet for Koala bears.  

“Kookaburra sits on the old gum tree, Merry merry king of the bush is he.” – Kookaburra Song, Australian Nursery Rhyme by Marion Sinclair

Identifying a Eucalyptus tree

With its fragrant blue-grey leaves and peeled bark, Eucalyptus is a very fast-growing tree. It can break 2.5m a year, with some variants growing up to 90m over their lifetimes. In recent years, Eucalyptus has become a highly popular foliage to use in wedding bouquets, interior styling and Christmas centrepieces, due to its fragment scent and ability to add bulk to floral arrangements. 

Younger specimens will have round, paddle-shaped leaves while adult trees have long, narrow leaves that hang downwards to avoid glare from the harsh sun. Because the trees grow so quickly, they shed layers of their bark each year, which results in a distinctive, peeled trunk. Some variants of the species can produce bark in a spectacular range of colours, in particular, the Eucalyptus Deglupta which has a bright green inner bark and an outer bark that can be blue, orange, purple and maroon. During its shedding season, this can result in a multi-coloured rainbow display that is certainly a remarkable sight. 

The name Eucalyptus comes from the Greek words eu (well) and calyptos (covered) after the little caps known as operculum that form when the buds expand and the flower petals cohere. The fruit will be surrounded by a woody cup-shaped receptacle that keeps minute seeds safely tucked away. Because the operculum is composed of the fused petals, the Eucalyptus has clusters of fluffy stamens instead, which are easily mistaken as petals. As the stamens expand, the operculum is pushed off, splitting away from the base of the flower.

Eucalyptus leaves are low in nutrition, highly fibrous, and extremely poisonous to every animal except koalas, greater gliders, and ringtail possums. The toxins are produced from oils secreted through the leaves, acting as a deterrent to insects and animals. One amazing way we have made use of this is by planting the trees in areas stricken with Malaria to keep the mosquitoes away. 

Natural medicinal properties of the Eucalyptus

Distilled from the fresh or partially dried leaves of the tree using steam, Eucalyptus oil has been used for hundreds of years for its many health and wellness properties. Only 20 variants of the species produce enough Essential Oil for commercial purposes, mainly the Eucalyptus Globulus. Eucalyptus oil can help to fight infections due to its outstanding antibacterial properties, to reduce swelling as a natural anti-inflammatory and can ease sinus pressure and related headaches.

Eucalyptus helps to clear nasal passages and bronchial tubes, giving relief to those with stuffy noses and making it easier to breathe. Today, it is common for people to hang branches in the shower at home to help with congestion, or to diffuse it with peppermint oil in the house when someone has a cold.  Many a steamy sauna has included a sprig of Eucalyptus to help clear the air. 

Medicinal eucalyptus oils and eucalyptol are extensively used as an active ingredient of cough lozenges, inhalation sprays, drops, gargles, mouthwashes, toothpaste, embrocation balms, ointments, liniments, and soaps. The oil is also an excellent rub for muscular aches and pains and can be added to the laundry wash for its cleaning, deodorising and antiseptic properties.

It is thought by most that a German botanist first discovered the tree’s antiseptic properties, but actually, the tree’s medicinal attributes have been well known by the Australian Aborigines for generations who call the tree ‘kino’, using it as a cure-all remedy. They consider it to be their holy tree and burn branches during their smoking ceremonies which is believed to ward away bad spirits. 

Behind the bark: uses for Eucalyptus timber… 

Due to these special health properties, the Eucalyptus has been grown commercially across tropical and subtropical regions. Eucalyptus is also a valuable source of hardwood and while the leaves of all variants contain some eucalyptus oil, only 20 have enough oil of commercial value to be exploited. Only 10 variants account for almost the entire world’s production. It’s generally understood that good timber-producing eucalyptus trees contain very little oil and those utilised for their oil produce poor quality timber.

Eucalyptus can be a very sustainable material to use. They grow quicker than other types of trees, which will not hinder the number of timber products produced. The timber is easy to sand, polish and saw, and it takes paint and stains well. 

Eucalyptus timber can be made into floorings, furniture and bowls, but it is also frequently used in Australia for heavy or light construction. It grows straight and tall, so it works well for wall panelling, fencing and trellises. The Aborigines have been creating beautiful didgeridoo instruments for over 1,500 years from the hollowed-out trunks of Eucalyptus trees. 

We have all heard the phrase that money does not grow on trees, but this is actually the case with the Eucalyptus. It certainly takes ‘gold leaf’ to an exciting new level, as Australian scientists discovered particles of the precious metal on the surface of the leaves. In their naturally hot and arid habitats, Eucalyptus trees can grow their roots to great depths to reach water and nutrients in the soil. It was thought that this causes them to draw up tiny amounts of gold through their roots and vascular systems. While there isn’t enough gold on the leaves to excite the prospectors, Eucalyptus trees might be able to help miners to discover new underground deposits without having to invest in trial digs. 

How to grow a Eucalyptus at home

Being an evergreen, the Eucalyptus is an incredibly popular tree to have in the garden. It is highly recommended that you speak to a horticultural expert to assess which variant of the species is right for your garden. Consider how big you want your tree to grow, and how much maintenance you want to commit to, which might help you decide. 

It is good to start small as these trees grow so quickly. Young Eucalyptus trees are very sensitive and need to be treated with care. They love the sun, so need to be positioned somewhere where they will get lots of light but are still sheltered from the wind. Initially it is advisable to grow them in pots, so you can move them inside in the event of frosts, but they need to be moved to the ground before they get too large, otherwise, they do not grow proper root systems and risk toppling over. Experts recommend repotting your tree every two years. The compost needs to be stable, long-lasting, free-draining, and moisture retentive.

It is no wonder that the Eucalyptus tree is still as popular as ever, with so many uses it is a truly magnificent tree.