Australian Mistletoes: unwrapping the mysteries of these intriguing native plants

Mistletoes are a fascinating and diverse group of parasitic plants found throughout Australia. Yet mistletoes often get a bad (Christmas) wrap!

However when it comes to Australian species, their naughty (not nice) reputation is somewhat unfounded. Australian mistletoes are not toxic; they are not introduced species; and while they are parasitic, they do not necessarily kill trees. Though they could definitely be accused of being a little needy…lacking roots they depend on other plants for survival.

David Watson first became fascinated with mistletoes as a child, when he encountered strange green clumps in growing in Plane trees and Pin Oaks in suburban Melbourne. Now with the release of his updated second edition of Mistletoes of Southern Australia, he has the chance to dispel some of the myths and misunderstandings that surround these distinctive and beautiful Australian native plants, as well as raise awareness of them too.

In Mistletoes of Southern Australia he focuses on the 47 species found in the southern region of Australia (occurring in Victoria, New South Wales, South Australia and the southern half of Western Australia). David acknowledges that this is not the definitive volume on the species – in fact he hopes that the book highlights the critical gaps in our research and understanding of Australian mistletoes, and inspires a future companion piece on the northern species.

Aussie, Aussie, Aussie (well, except for Tasmania)

Australia is home to 97 species of mistletoe, and in addition to forests and woodlands, they can also be found in deserts and heathlands, as well as urban and agricultural areas, making them some of the continent’s most cosmopolitan plants!

Despite popular opinion mistletoes are not introduced. Many people believe they are exotic weeds, like willow and blackberries, but this is not true.

And although mistletoes are found throughout mainland Australia, there is no mistletoe in Tasmania! Fossil plant species indicate they did grow at one time, but probably became locally extinct in Tasmania during the last ice age.

The parasitic habit – does it really suck?

Australian mistletoes depend on their host plants for all their water and nutritional needs – in other words they are a parasite. And while they could be considered freeloaders, perhaps a more poetic way to describe their relationship is that they are permanently bonded. The fates of both plants inextricably connected – doesn’t that sound much nicer?

And while they can be called a parasite, very few can be called a killer. This inextricable bond means that the well-being of the host plant is in direct interest of the mistletoe, so starving or killing the host plants, compromises their own survival. That’s not to say there is no discernible effect – there is often a reduction in access to water and nutrients for the host plant, and multiple infections can have dire consequences. In extreme cases, this can shorten the tree’s life by making it more susceptible to drought, insect attack or fungal infection.

Twin-leaved Mistletoe (illustration: Robyn Hulley)

Square-stemmed Mistletoe (illustration: Robyn Hulley)

Forked Mistletoe (illustration: Robyn Hulley)

Kurrajong Mistletoe (illustration: Robyn Hulley)

Harrow-leaved Mistletoe (illustration: Robyn Hulley)

Pale-leaved Mistletoe (illustration: Robyn Hulley)

Shiny-leaved Mistletoe (illustration: Robyn Hulley)

Coast Mistletoe (illustration: Robyn Hulley)

Our animals appreciate Australian mistletoes too:

• Australian mistletoes can boost wildlife populations in agricultural landscapes, by providing animals with food, shelter and nutrient-rich leaf litter.

  

• Many iconic bird species such as the endangered Regent Honeyeater depend on various mistletoe species as a source of nectar, and for nesting sites. Retaining sufficient mistletoe plants in woodland habitats forms part of the management plan for this particular species.
• The succulent leaves of mistletoes provide valuable nutrients for a wide variety of our invertebrate friends, including beetles, spiders, caterpillars, moths and butterflies. In fact twenty-three butterfly species depend on mistletoe as principal food plants.
• With heat-waves expected to become more severe and frequent, the densely branched clumps of mistletoes can offer a cool respite during the heat of the day for many animal species. They are vital in semi-arid and arid regions where shade is scarce.

As well as being the definitive guide to the 47 mistletoe species found in southern Australia, Mistletoes of Southern Australia is illustrated with beautiful watercolour paintings by artist Robyn Hulley, as well as stunning photographs of mistletoes and the animals that depend on them. The second edition of David’s book is available now through bookshops, or order online through our website.

David M Watson is an ecologist with a long-standing interest in mistletoes. In addition to the ecology of parasitic plants, his research focuses on developing solutions to habitat fragmentation and managing biodiversity in agricultural landscapes.