To describe Yellow Gum as a single tree type is extremely difficult, as this species has so many different forms. It has a native range extending from southern NSW through Victoria into most of South Australia, including Kangaroo Island. Rodger Elliot, in his Encyclopedia of Australian plants, identifies these horticultural characteristics of E. leucoxylon:
- Suited to most areas, except the tropics,
- Long flowering period,
- Adapted to most soils, including alkaline soils,
- Drought and frost tolerant,
- Resistant to smog,
- Moderately fast growing, and
- Excellent for shelter, shade and wind erosion control.
Poor branch attachment and short lifespan are possibly the only limitation to using E. leucoxylon in the landscape. To overcome these problems, specific provenance and seed selections are recommended.
E. leucoxylon ssp. connata
This is the Melbourne subspecies that can be seen in many areas of central and north Melbourne. It grows to an eventual height of approximately 12m by up to 10m broad. This eucalypt is very tolerant of heavy soils with a high clay fraction, and is also adaptable to soils with an alkaline pH. The flowers are yellow, showy, but without the impact of the pink-flowered forms. Authorities, including D. Beardsell, believe that the branch attachment is better on this subspecies than on some others.
E. leucoxylon ssp. megalocarpa:
This large-fruited subspecies is the most commonly grown selection of Yellow Gum. It is typically pink-flowered, and is similar to that sold as ‘Rosea’. Growing to a height of 7m, it is suitable for growing in height-restricted areas. Some arboriculturists worry about this tree breaking up after 15-20 years’ growth, but as it is fast-growing to its mature size, it does offer 10+ years of good canopy in the streetscape.
Metropolitan Tree Growers are please to offer an “ELITE” form of this tree. These elite seedlings have come from a seed orchard developed by Dr David Beardsell from DSE Victoria. Dr Beardsell selected the best forms and flower colours from an extensive collection of E. leucoxylon ssp. megalocarpa, and planted these trees in Mt Gambier. We have harvested seed from the best of these trees, and believe that the resulting trees will be more uniform, have better branch attachment, and be more uniformly red-flowering. We will be labelling trees from this seed orchard as “Metropolitan Elite” strain.
E. leucoxylon ssp. pruinosa
This tree comes from inland South Australia , where it grows on both well-irrigated and droughty soils. On poor soils with low rainfall, it typically grows to 4m, but with irrigation it can grow as tall as 17m. It is typified by waxy new growth and buds; the flowers are normally a pale yellow, although some will be pale red, to pink.
Eucalyptus leucoxylon ‘Grafted cultivars’
These cultivars have been selected from street and reserve plantings where individual trees showing exemplary form or character have been identified. Budwood from these plants is then grafted onto E. leucoxylon seedling rootstocks to allow the clonal expression of these desirable attributes. Humphris Nurseries have done the grafting. We expect these trees to have more predictable branching patterns, better suited to urban use than are many current seedling lines.
‘Horsham’ is a grafted form with pink flowers. Originally selected by Dr. David Beardsell, this form will grow to 4 – 5 m tall and has a rounded crown to 4 m wide. It will have the same environmental tolerances as the species but can be used in locations where space is more constrained..
‘Austraflora Scarlet (new name likely)’ is a selection made by Bill Molyneaux.
‘Moreland Elite’ was selected from a street planting in West Coburg. The parent tree has grown with a straight trunk with good branch angles. Its flowers are cream.
Eucalyptus leucoxylon var. megalocarpa ‘Rosea’ is a grafted form with deep scarlet flowers. Flowering can continue from April unitl October. This form was originally selected by Humphris Nursery and grows 5-6 m tall with a relatively narrow canopy to 3.5 m wide. It will have the same environmental tolerances as the species.
We have found that these sand-inhabiting eucalypts tend to grow very sparse root systems early in the season. It seems that the root systems grow quite strongly in winter and will fill the containers thoroughly by July or August. For 40 litre stock, it can take a full 12 months to get a root system fully established.
Elliot , R. & Jones, D. 1986-Encyclopedia of Australian plants.Lothian Publishing Company, Melbourne Victoria.
Society for Growing Australian Plants Maroondah, Inc. 1991 Flora of Melbourne. SGAP Maroondah, Inc., Melbourne Victoria.