Gaining a better understanding of ornamental eucalypts

The eucalypts, or gum trees (genera Eucalyptus, Corymbia and Angophora), contain unique flora with over 800 species throughout Australia (and its closest northern neighbours) and represent one of Australia's greatest floral icons. Eucalypts play a vital role in all Australia's ecosystems, providing habitats for native birds, insects and animals. Eucalypts inhabit a diverse range of habitats, from dry deserts to lush rainforests and windswept coastal cliffs. There are a great number of species that are rarely seen in cultivation, with highly ornamental flowers, leaves, buds, and fruit, and small habits. Researchers at the University of Adelaide program have been investigating the development of ornamental eucalypts for over 15 years, using controlled pollinations to investigate relationships between species and to breed new interspecific hybrids. The new hybrids then undergo selection and development for suitability in different markets. Clonal propagation is a major bottleneck in new cultivar development. Grafting is commonly used for some cultivars of flowering gums; however, this program has sought to develop tissue culture methods for propagation of selected forms, as this will provide significant commercial advantages in the future. Additional research has been conducted into aspects of reproductive biology of eucalypts, including pollen viability after storage and stigma receptivity. This paper will report on the program and describe the way forward, with exciting new developments.