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Temperate Area Eucalypts
The eucalypts comprise all plants from the genus, Eucalyptus, with about 800 species, and two smaller genera, Angophora (the apples) and the recently described Corymbia (the bloodwoods). They are common and widespread throughout most of the Australasian region (notably absent from New Zealand), from the southern Philippines in the north, where Eucalyptus deglupta occurs, south to the southern most tip of Tasmania, where the type for the genus, E.obliqua, was first collected. Most species, however, grow in temperate areas and many of the most ornamental and useful species occur in southern Western Australia and South Australia.
As the number of temperate area eucalypts is in the hundreds, I will only briefly outline a small number. With the theme of temperate area treasures, I have chosen many that occur in remote or inaccessible areas, but are well worthwhile in cultivation in temperate areas.
South Australia has many eucalypts that remain treasures. A close relative to the Tasmanian blue gum (E.globulus) is E.bicostata, and amazingly it has recently been found as an isolated population on a mountain near Burra in South Australia. Previously known from the Snowy Mountains in New South Wales and Victoria where it grows to 60 metres tall, the trees near Burra are low and stunted. These E.bicostata were certainly not planted as they form tree rings up to 10 metres across and must be hundreds of years old.
On the tops of the highest peaks in the Flinders Ranges grows an unnamed relative of E.goniocalyx. It has silvery juvenile leaves like E.goniocalyx, whose juvenile leaves are used in floral arrangements, but differs in the smooth bark and smaller leaves, buds and fruits. Another eucalypt known from only a few mountains in South Australia is E.gillenii, which grows in the crevices of rock domes in the far north-west of the state. E.gillenii also grows in Northern Territory and Western Australia but makes an attractive bushy mallee in cultivation in temperate areas.
Commonly cultivated South Australian ornamental eucalypts include E.cosmophylla, an endemic to the Mount Lofty Ranges and Kangaroo Island in South Australia with large white flowers, and E.leucoxylon, of South Australia and Victoria. There are four subspecies of E.leucoxylon, with subsp. megalocarpa being the best for coastal areas, with flowers ranging in colour from white to dark red.
One of the more common species throughout the temperate regions of Australia is E.leptophylla. It is quite variable across its range, from Balladonia in Western Australia to western New South Wales and Victoria. Most forms are small, slender mallees. It should be cultivated more because of its glossy, green leaves and masses of colourful buds before flowering.
A commonly cultivated bloodwood eucalypt that is very attractive in flower is Corymbia ficifolia. Native to a few sandy swamps in south-west Western Australia, where it is relatively unattractive, in cultivation it often forms a dense small tree with masses of red or vermilion flowers.
Two unrelated eucalypts are generally regarded to have the narrowest leaves of all the species and both grow very well in temperate regions but are rarely cultivated. E.angustissima is a mallee to 4 metres tall that is indistinguishable from broombush (Melaleuca uncinata) from a distance. E.perangusta is a shrub to 3 metres tall, related to E.leptophylla and E.formanii, but with narrower leaves than both.
Many east coast species are planted in home gardens and eventually reach sizes that are too great. The are often planted because of their attractive bark and leaves, such as E.pulchella, a Tasmanian endemic, but over time even it grows to 25 metres tall. There are some lesser known east coast eucalypts that, although very attractive, are low growing. E.serpentinicola is one such species, with leaves and bark like that of E.pulchella, but which grows to only 4 metres tall in high rainfall forest in New South Wales.
A group of eucalypt species that has perhaps the most ornamental features, is series Curviptera, and most of the species of this series occur in temperate areas. E.macrocarpa, from the wheatbelt of Western Australia, is possibly the best known example, there are two subspecies, with subsp. elechantha being lower growing and more compact. Both subspecies, with their silvery leaves and red flowers, are extremely ornamental. E.youngiana, from the Great Victoria Desert of Western Australia and South Australia, has massive flowers and fruits like E.macrocarpa, which range in colour from pale yellow to red. Similar, and closely related to E.youngiana is E.pyriformis, from the northern wheat belt of Western Australia.
Also of the same series is E.leptopoda, a "whipstick" mallee that would prove useful for smaller gardens. Closely related to E.leptopoda is E.synandra whose flowers are white but fade to pink with age. Both species are slow growing but reliable in temperate areas. E.kingsmillii is another from the series with large sculptured buds and fruits of which there are two subspecies. E.kingsmillii subsp. alatissima with red flowers and subsp. kingsmillii with yellow flowers. With its prominently winged buds and fruits and red flowers, subsp. alatissima, from the Great Victoria Desert of South Australia and Western Australia, should be cultivated in drier, temperate areas.
Other very ornamental eucalypts of the Great Victoria Desert include E.wyolensis (South Australia only), a large-leaved and large-flowered relative of E.gillii and E.pimpinana (South Australia and Western Australia), a species with no close relatives that grows only to 2 metres tall and has bright yellow flowers.
One of the best small eucalypts for temperate areas is E.preissiana. Occurring naturally along the south coast of Western Australia, in cultivation it forms a bushy mallee to 4 metres tall with large, bright yellow flowers. The are two subspecies, but only subsp. preissiana is common in cultivation. The recently discovered subsp. lobata is far superior to subsp. preissiana, with a bushier habit and much larger leaves, flowers and fruits.
Related to E.preissiana but incredibly dissimilar is E.sepulcralis, from the Barren Ranges of Western Australia. Its small, cream flowers are relatively insignificant. However, its amazing, thin-stemmed weeping habit, that it shares only with E.pendens, makes these two eucalypts a novelty that grow well over much of temperate Australia. Where E.sepulcralis and E.preissiana grow together, natural hybrids of intermediate form occur, and these have been named E.chrisantha because of the light yellow flowers.
Many other Western Australian eucalypts are highly suited to cultivation in temperate areas where they form ornamental plants. E.histophylla, whose flowers had not been seen until flowered in cultivation at Currency Creek Arboretum, is a fast growing large mallee with masses of yellow flowers appearing at an early age. The related E.densa has pale yellow flowers and bluish leaves. Growing as an understorey to it in the Lake King area is E.depauperata, a dwarf form of E.eremophila with bright yellow flowers.
This is just a small selection of some of the more interesting eucalypts occurring naturally in, or suitable for, temperate Australia. There is at least one species of eucalypt suitable for almost any site in the Australian garden. In fact the majority of all eucalypt species are not huge forest trees but are poorly known mallee species of immense horticultural potential.
This article is a reproduction of a paper presented at the ASGAP 19th Biennial Seminar which was held at Annesley College, Adelaide, 30 September to 3 October 1997.
Dean Nicolle has had a life long interest in eucalypts and recently graduated with an Honours degree in Botany from the University of Adelaide. He has travelled extensively in Australia to study, collect and photograph eucalypts in their natural environment, and has an arboretum at Currency Creek, south of Adelaide with approximately 750 eucalyptus species growing, including all South Australian species.
Dean is the author of "Eucalypts of South Australia". South Australia has 95 different native eucalypts, including 20 never before illustrated in colour. All are fully described and illustrated in this book. The book (over 200 pages with more than 380 full colour illustrations) allows the identification of all species, gives clear maps and descriptions of where to find them in the bush and gives useful advice on how to grow each species and what uses each can have.
The Eucalypts of South Australia has been designed and written for anybody interested in identifying and growing native trees, not just those familiar with the botanical language. The book will be a valuable companion to all South Australian naturalists, gardeners, farmers, pastoralists, botanists, foresters, students, bush walkers and growers of native trees.
Price: $20.00 (plus $3.00 postage within Australia)
Ordering details can be found on the Currency Creek website.
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Australian Plants online - December 2002
Association of Societies for Growing Australian Plants