No. 6 Eucalyptus IN THIS ISSUE DEucalyptus This issue of Seed Notes The name Eucalyptus comes will cover the genus from the Greek eu meaning Eucalyptus. well and calyptos meaning covered. It refers to the D Description flower bud that is covered D Geographic by the operculum or cap. The distribution and first Eucalyptus species were habitat introduced into cultivation D Reproductive biology around 1771. The genus is now one of the worlds’ most D Seed collection important, the main use being The yellow flowered Eucalyptus preissiana. Photo – Andrew Crawford D Seed quality for timber production. Some are used for draining marshy assessment species are very hard and areas due to their high water Description D Seed germination resistant to termites, while uptake. The genus has use Members of the genus others are soft and used for for apiarists due to the richness DEucalyptus (family Myrtaceae) D Recommended reading pulping for paper production. in nectar of the flowers. Trees are woody perennial shrubs The timber is also very and shrubs of many species and trees, mostly evergreen. important for fuel wood in are widespread in amenity They may have persistent many developing countries. The horticulture. The bark and fruit or deciduous bark, rough or bark has been used for tannin are often used in craft making smooth, or a combination of production although it is now while the leaves produce many the two and the bark type is rarely employed. The leaves of shades of colours and are used one means of identification a number of species are utilised in wool dyeing. Many species of species. The juvenile leaves for ornamental floristry. Trees provide food and habitat for often differ from the mature have been used for wind and native animals (e.g. koalas) ones and this can assist in water erosion control; others and birds (e.g. parrots).D identification. The foliage ranges in colour from bright green to dull olive green and silver-grey. There is a strong mid vein in the mature leaves and oil glands may be prominent. The leaves contain oil that in some species is extracted for its medicinal and industrial properties. The flowers consist of an inflorescence of between three and 35 flowers in a umbel (all the individual flower stalks arise in a cluster at the top of the stem). The numerous stamens of the flowers may be white, cream, yellow, orange or red. The fruit is a capsule, which may be woody and comes in all shapes and sizes, further assisting in identification of species. Variations in flower colours in Eucalyptus ficifolia. Photos – Kate Brown D
Seed Notes 6 page 1 Geographic distribution and habitat Seed collection Eucalyptus is the second largest Eucalyptus species generally Dgenus in Australia and all but produce copious quantities about eight species are endemic. of seed annually and the Members of the genus occur fruits may take a year to throughout Australia, from sea mature from flowering. level to over 2000 metres in The capsules are mainly height. They occur in a variety woody, hard and may be of habitats from exposed coastal brown when mature, and sites to closed forests to dry located on older wood. inland regions. Most occur in Check to see that seed is dry or wet sclerophyll forests Approximate distribution of ripe by cutting the capsule and woodlands with a few found Eucalyptus in Australia. carefully with a pair of in the rainforests of the tropics. secateurs. The endosperm Eucalyptus species grow on a range of soil types, from well drained to should be white and firm, poorly drained or even waterlogged; from acid to alkaline; from sandy with a brown to black seed soils to rocky clay loams. There is a wide array of growth habits in the coat. The fruits should genus Eucalyptus. They may be very tall trees or they may be almost not be green, and if the prostrate. Trees or shrubs may be multi-stemmed (mallee) or with a valves on the capsule look straight trunk and branching at a height (mallet). Many species can as if they are beginning to be coppiced during harvesting, resprouting from the base. Although open then the fruit should some species are tolerant to saline soils, the survival of several species be ripe enough to collect. Collecting Eucalyptus dolichorryncha. in the eastern wheatbelt The seed of most species Photo – Anne Cochrane of Western Australia is of Eucalyptus are easy to threatened by rising salt collect, although seed from levels and waterlogging. tall trees can only be reached Some species, such as by climbing or using long-handled pruners. The capsules E. marginata (jarrah), are generally shed seed on maturity and the timing of collections susceptible to the dieback may be crucial, although many species hold seed for a year. It disease, Phytophthora is important that unopened capsules are collected. Capsules cinnamomi. will release their seed if kept under warm, dry conditions from A range of fruit shapes and sizes. a day to several weeks. Photo – Andrew Crawford D DReproductive biology Many species produce copious quantities of nectar that attracts insects, birds and small mammals such as honey possums. Plants may be insect, bird and sometimes animal pollinated. Sawflies and native bees are implicated in pollination. The genus is renowned for its ability to hybridise between species, giving rise to a range of variable combinations. Some species do not flower every year and may have years when flowering is phenomenal. Eucalypts are divided between those that are killed by fire, Above: Eucalyptus buds. regenerating from seed and those that Right from top: Eucalyptus synandra, have a lignotuber, a below or partially- Eucalyptus petila, Eucalyptus argutifolia. below ground root swelling that allows Photos – Anne Cochrane them to resprout after disturbance, such as fire. Seed is dispersed by gravity and by wind. D
Seed Notes 6 page Eucalyptus aquilina.
Eucalyptus erectifolia.
Eucalyptus creta.
Eucalyptus dolichorrhyncha.
Eucalyptus macrocarpa.
Photos – Anne Cochrane Robin Probert from the Millennium Seed Bank collecting Banksia tricuspis seed. Photo – Andrew Crawford DSeed quality assessment Germination of seeds The seed of Eucalyptus are The germination of Eucalyptus present within the fruits Dseed is generally easy without the or capsules in association need for pre-treatment. Some with chaff, or non-viable montane species benefit from seed. For some species it is cold stratification (putting seed in very difficult to distinguish a fridge for a few weeks before the chaff from the seed. conducting germination testing) The chaff is sometimes a prior to sowing. This is not necessary different colour or shape, with Western Australian species. Germinating Eucalyptus seed. but there is no white endosperm inside the chaff, and it has a Germination is generally very Above: Eucalyptus bennettiae. more brittle texture. A cut test and count can be performed on high (provided good seed, not Below: Eucalyptus rhodantha. the seed and chaff to give an estimate of the number of seeds chaff, is used) and seed maintains Photos – Anne Cochrane within a given weight. This is viability for a long time provided often easier than to separate it is stored under cool, dry seed from chaff. conditions. The seed responds D well to surface sterilisation of the seed coat with a diluted solution of bleach (10 per cent). This helps Eucalyptus seed and chaff. prevent fungal infection during Above: Eucalyptus bennettiae. germination. Left: Eucalyptus angustissima. Photos – Anne Cochrane D
Seed Notes 6 page Seed Notes for Western Australia
These Seed Notes aim to provide information on seed identification, collection, biology and germination for a wide range of seed types for Western Australian native species.
They have been written and compiled by Anne Cochrane, Manager of DEC's Threatened Flora Seed Centre. Concept by Grazyna Paczkowska. Designed by DEC’s Graphic Design Section.
The Seed Notes are available from www.naturebase.net Top: Bark colouration in Eucalyptus creta. Above: Eucalyptus synandra. Photos – Anne Cochrane
Seed Notes Recommended reading are published by Boland, D. J., Brooker, M. I. H. and Turnbull, Sharr, F. A. 1978. Western Australian Plant the Perth Branch of the J. W. 1980. Eucalyptus Seed. CSIRO Australia. Names and their Meanings. A Glossary. Wildflower Society of University of Western Australia Press, Perth. Western Australia (Inc.) DBrooker, M. I. H. and Kleinig, D. A. 1990. with assistance from Field Guide to Eucalypts. South-western and Turnbull, J. and Doran, J. 1987. Seed the Western Australian southern Australia. Inkata Press, Melbourne. development and germination in the Lotteries Commission Myrtaceae. In Germination of Australian Elliot, W. R. and Jones, D. L. 1984. and the Department Native Plant Seed. P. J. Langkamp (ed) Encyclopaedia of Australian Plants Suitable of Environment and Pp. 46–57. Inkata Press, Melbourne. for Cultivation. Volume 4. Lothian Publishing, Conservation (DEC). Melbourne. D 2007501-0308-1
Seed Notes 6 page