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Next time you get a Christmas kiss under the mistletoe, here’s something to think about.
Mistletoes are parasites. 91 species are found in Australia and of them, 66 species are endemic.
Australian Mistletoes can be found from our Alpine Regions to the Deserts, the Tropics and all regions in between. They are found in all Australian mainland states, but Tasmania remains mistletoe free.
As parasites, Mistletoes take their water and nutrients directly from their host trees. However they manufacture their own carbohydrates using photosynthesis. Mistletoes attach to their hosts above the ground and are distinguished by their growth form, being shrubby, woody plants.
Mistletoes attach to their host via a specialised organ called a haustorium. This structure serves two purposes, anchoring the mistletoe firmly to its host tree, and tapping directly into the sap of the host tree, allowing water and dissolved nutrients to flow directly to the mistletoe.
The most diverse genus of mistletoe in Australia is the genus Amyema, with 39 of almost 100 species native to Australia.Image Could Not Be Found
Just like other flowering plants, mistletoes begin life as a seed. Mistletoe seeds are surrounded by a sticky translucent pulp known as viscin.
The seeds are eaten and distributed by birds. Eastern Spinebills, Painted Honeyeaters, Mistletoe Birds and many others are attracted to the coloured fruit. When the fruit is eaten the seed and its sticky coat is not digested in the gut of the bird. The birds quickly defecate the undigested seed pulp, depositing the seed onto tree branches where it will then germinate
The sticky pulp is important for two reasons. It attaches the seed firmly to its host tree and it acts like a sponge to absorb moisture from rain and dew for the developing embryo within the seed. Image Could Not Be Found
Once seed germinates and bonds to its host tree, the bond is permanent and the fate of the mistletoe depends solely on the fate of the host tree. It is in the interest of the mistletoe to have a negligible effect on its host tree, so that the host and the mistletoe can both survive. However when the host tree is infected by a large number of mistletoe plants, host vigour and survival can be compromised, leading to the decline and ultimately death of both the host tree and the mistletoe. Image Could Not Be Found
Mistletoe flowers have abundant nectar and the nutritious fruit attracts many types of birds such as woodswallows, shrike-thrushes, trillers and lorikeets that regularly feed on the nectar. Emus, butcherbirds, currawongs and ravens will
gorge on the sticky fruit. Other native animals that feed on the mistletoe include gliders, fruit bats and possums. Several species of kangaroo have been reported as eating mistletoe.
Many types of mistletoe resemble their host very closely. The Buloke Mistletoe has needle like foliage and dark coloured leaves making it almost impossible to locate when it is not flowering. Box Mistletoe has leaves approaching 40cm in length when growing on Manna Gums, but when growing on various species of mallee has leaves less than 2 cm in length, a twenty fold difference in size.
Mistletoes also provide roosting and nesting sites for birds and animals in or on the rigid framework of the branches.
Amyema miquelii – Box Mistletoe
The Box Mistletoe is one of Australia’s most prolific mistletoes. It is the most common species found west of the Great Dividing Range and is found in all mainland states. While it is mainly a Eucalypt dependent parasite it is sometimes found growing on acacias.
Box Mistletoe forms a large pendulous mistletoe with shiny leaves and red flowers that are borne in groups of three on individual stalks. What makes this mistletoe easy to distinguish from its host tree is the bronze or yellow hue of the leaves when the plant is exposed to strong sunlight, yet plants that are shaded will still have green leaves.
The Box Mistletoe is found in open forests and
woodlands dominated by eucalypts. The red flowers are comprised of pinkish petals that open to reveal
bright red stamens and style. The fruit is smooth and mostly yellow – cream in colour.
Being the most abundant Australian mistletoe, it can often be found in very high numbers. There are numerous environmental reasons for this abundance that can also indicate that the natural habitat is out of balance. Many studies of Mistletoe have been carried out in various areas of Eastern Australia During the mid 1980’s up to 40% of eucalypts in the
Clare region were infected so heavily that many trees were severely stressed and showed signs that they would not survive.
Mistletoe Action Groups have been formed and their efforts and further research have led to a better understanding of how to manage the spread of mistletoe. A quarter of a century later the actions of these groups have saved countless trees from death and the eucalyptus trees – and their mistletoes - are looking healthy again.Image Could Not Be Found
For a greater in depth detailed report and more images, please refer to my accompanying blog
Cheers
Stephen