Designer gum trees bred for city living

By Joanna Egan 4 June 2013
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Researchers are creating new species of eucalypt to suit Australian urban landscapes.

SCIENTISTS HAVE DEVELOPED NEW eucalypts specifically designed for city landscapes.

The South Australian researchers have selectively bred eucalypts to produce trees with characteristics suited to home gardens, public parks and other urban areas.

In time, these trees could replace many of the exotic pines and foreign evergreens that currently line our streets.

“Eucalypts are beautiful trees that deserve a place in our hearts, our homes and our urban landscapes,” says Dr Kate Delaporte, lead researcher and horticulturalist at the University of Adelaide.

Designer eucalypts for urban landscapes

Kate aims to accentuate the characteristics in gum trees that are preferred by urban planners, such as straight trunks and particular flower colours. At the same time, the team is trying to increase the plants’ tolerance to a range of soil types and environmental conditions.

“I’m hoping that having a new range of eucalypts tailored to our smaller gardens will encourage more people to plant them,” says Kate. “This will increase habitat for native fauna, birds and insects.”

The “designer” trees are produced through controlled pollination, in which pollen from select individuals is placed on the reproductive organs of other select individuals. The resulting seeds are harvested and grown to maturity.

Once the young trees flower, their physical characteristics are assessed. “The individuals that have the combinations we want are then moved through to the propagation phase,” says Kate.

New eucalypts: Nullarbor rose and Nullarbor lime

The plants are propagated, or reproduced, in three ways: from cuttings (a piece of the plant is cut off and grows roots of its own); by grafting (a piece of the plant is grafted onto a suitable rootstock species); and via tissue culture (in a laboratory, new seedlings are cloned from the leaves, seeds and stems of the original plant).

“It’s a slow process that can take many years,” says Kate.

Two new varieties were released last year, the Nullarbor rose (Eucalyptus youngiana x E. macrocarpa) and Nullarbor lime (Eucalyptus pyriformis x E. macrocarpa), which are crosses between three different Western Australian eucalypt species.

The team is currently developing new varieties from the Corymbia genus. These will include traits from the red flowering gum, which is known for its bright, summer flowering display.

These species are still under trial, however Kate hopes they will be available in the next few years.

For more information, see the project website.