EUCALYPTS

Select and cultivate appropriate varieties of Eucalypts in different situations.

Why Do People Grow Eucalypts?

Eucalypts can be used in many different situations. Among the more than 500 species you can find types to use in a very wide range of situations:
They are excellent for use as firewood, the leaves can be cropped for oil, the flowers are excellent for honey, some make excellent building or construction timber, farmers use Eucalypts for windbreaks or shelterbelts, conservationists can use them for reclamation of damaged countryside, or stabilisation of erosion prone areas and to support local wildlife, they can also be used in home gardens, parks, street trees etc.

Timber
The best known Australian native trees, the eucalypts, are grown extensively for timber and paper pulp production, both in Australian and overseas plantations. Their main disadvantage is the long period of time required to produce a harvestable crop. For example, mountain ash (Eucalyptus regnans) typically takes more than fifty years before it can be harvested. Other species, though, can produce commercial timber in a shorter period; for example, spotted gum (Eucalyptus maculata) can be harvested in less than twenty years

Oil
The flavour and fragrance of scented plants such as eucalypts are due to the aromatic compounds in their flowers, leaves, and bark. Those chemicals not only have a unique smell and taste, but they also contain valuable chemicals which have both medicinal and disinfectant properties. When these chemicals are extracted by distillation, the resulting product is a volatile, colourless, oil-like material. Essential oils from eucalypts are used in food flavourings, pharmaceuticals, soaps, disinfectants, toiletries, fragrance, and other industries. Different eucalypt species have different properties also.

Cut Flowers

The foliage and flowers of some eucalypt species are prized by the floristry industry in many countries. 

Lesson Structure

There are 8 lessons in this course:

1. Introduction
   • Scope and Nature of Eucalypts
   • Taxonomy; Review of the system of plant identification
   • General characteristics of the Myrtaceae Family
   • Subdivisions of the genus Eucalyptus; Macrantherae, Renantheroideae, Renantherae, Terminales, etc
   • Popular subdivision into gums, box, stringybark, messmate, mallees, etc
   • Hybrid Eucalypts
   • History of Eucalypt taxonomy; botanical renaming and Corymbia
   • Plant Name Pronunciation
   • Eucalypt Flower Structure; inflorescence, flowers
   • Eucalypt leaf structure
   • Resources and further Information; nurseries, seed, herbaria, etc.
2. Culture
   • Soils and Soil Structure
   • Soil Chemistry
   • Nutrition
   • Fertilizers
   • Summary of Eucalypt characteristics and culture
   • Planting technique
   • Tree Guards
   • Pest & disease that are commonly found on Eucalypts
   • Watering
   • Weed Control
   • Soil Testing
3. Propagation
   • Scope and nature of Eucalypt Propagation
   • Treatment of Seed during Germination
   • Substrates for starting seed
   • Transplanting Seedlings
   • Potting up
4. Commonly grown Varieties of Eucalypts
   • Scope and Nature of Eucalypt Culture in Australia and elsewhere around the World
   • Review of many commonly cultivated Eucalyptus and Corymbia species
5. Other important groups.
   • Introduction
   • Hybrid Eucalypts
   • Why Breed Eucalypts
   • Review of Mallee Eucalypts
   • Review of Gums
6. Lesser grown varieties.
   • Boxes
   • Bloodwoods
   • Peppermints
   • Stringybarks
   • Ironbarks
7. Making the best use of Eucalypts
   • Introduction
   • Timber Production
   • Oil Production
   • Where to Plant Eucalypts; amenity trees, natural and bush gardens, xeriscapes
   • Agroforestry
   • Techniques for Planting on Slopes
   • Planting on Arid Sites
   • Growing in Dry Areas; overcoming dry conditions, sandy soils
   • Eucalypts and Fire Management
   • Windbreak Planting
   • Plant Selection
   • Understanding Plant Interrelationships
8. Special Assignment
   • Problem Based Learning Project
   • Plan the establishment of a collection of different cultivars of Eucalypts
   • eg. Gums, Mallees, Tall Trees, Short Trees, or Dryland Species, suited to growing in a specified locality.

Aims

• Describe the classification of Eucalypts.
• Discuss general cultural requirements for growing Eucalypts.
• Propagate Eucalypts.
• Differentiate between identifiable characteristics and cultural requirements in a number of commonly cultivated Eucalypts.
• Discuss characteristics of a wider range of Eucalypt species.
• Describe commercial uses for a range of different Eucalyptus species.
• Plan the establishment of a collection of different cultivars of Eucalypts (eg. Gums, Mallees, Tall Trees, Short Trees, Dryland Species), suited to growing in a specified locality.

What are Eucalypts?

Eucalypts were first named and recognised in the late 1700's. Shortly after their discovery, a small number of these plants were separated into a different genus and called "Angophora". The only real difference between Angophoras and Eucalyptus are that the Angophoras have very small petals on the flowers and Eucalypts do not. 

Popular Species and Cultivars

Eucalyptus caesia  (Gungurru)
A weeping tree, normally 5-7m tall with sparse foliage but extremely attractive red or pink flowers and (depending on the form you have) white bark. Frost tender when young. Best suited to a well-drained soil. Plants will tend to fall over in heavy clay or compacted soils due to a poorly developed root system.

Eucalyptus calophylla
A medium sized, red to pink flowering tree from south-west Western Australia. It grows well in most temperate climates and is good as a specimen tree in a lawn.

Eucalyptus citriodora (Lemon Scented Gum)
(Now known as Corymbia citriodora)
Though often grown in home gardens, this is really a big tree for an average sized garden. It grows to 20m or more with a canopy spreading more than 12m in diameter. The flowers and foliage are so far away from the eye on a fully grown plant that they are not noticeable, however the smooth white trunk is spectacular and the scent from fallen leaves crushed under foot, definitely adds a special dimension to the garden. It is worth trying in any garden if you have the room. There is a small growing variety, usually sold as ‘Dwarf’ or ‘Compact’ which only grows to about half the usual size.

Eucalyptus macrocarpa (Mottlecah)
A small, often spindly plant with large blue-grey leaves and red flowers to 20cm or more in diameter. It is frost tender when young and must have a well-drained soil to survive. In medium to high rainfall areas, it is best grown in a sandy soil or on a raised bed.

Eucalyptus nicholii
A shapely tree to about 6m, with rough bark and fine blue-green leaves and a graceful habit. Grows well in most temperate areas.

Eucalyptus preissiana (Bell Fruit Mallee)
A bush plant, 3-5m tall with spectacular yellow flowers. Grows well in dry to medium rainfall areas. Needs very good drainage to succeed in areas where the annual rainfall exceeds 500mm to 600mm.

Eucalyptus scorparia (Wallangara White Gum)
A pretty, small tree to about 5 or 6m, with smooth cream bark and fine, glossy dark foliage, plum-coloured when young, with white flowers.

Eucalyptus sideroxylon (Mugga)
An ironbark, with an almost black trunk and greyish leaves. It grows to about 10m and does well in most parts of the country. Flowers are showy, in cream or rose-pink (E. sideroxylon rosea).

Eucalyptus torquata
A hardy tree, normally to 5m tall (sometimes to 10m) with red buds and pink flowers over summer. Grows well in a wide variety of climates though it prefers good drainage.

Eucalyptus viridis (Green Mallee)
Like most Mallee eucalypts this commonly forms several trunks arising from the one point, creating a bushy appearance. Growing to 5m tall and adapting to a wide range of climates, this is an ideal size for most home gardens.

EUCALYPTS FOR WARM CLIMATES
(eg. Far North Queensland, Darwin)
E. camaldulensis: 20 to 40m tall, depending on conditions and source of the seed it is grown from.
E. miniata (Darwin Woolybutt): To 15m tall and 5m spread with spectacular orange or red flowers. Must have well drained soil.
E. ptychocarpa (Corymbia ptychocarpa) (Swamp Bloodwood): To 15m tall and 7m spread, rich green leaves and white, pink or red flowers gives it a similar appearance to Corymbia ficifolia. Grows best in moist soils.
E. tetrodonta (Darwin Stringybark): To 20m tall and 10m spread, prefers good drainage, pale yellow flowers late winter.
Corymbia citriodoa syn. E. citriodora (Lemon Scented Gum): To 50m tall in the tropics.