Contributed by Ethan Mimnaugh,
Mooloolah Landcare Nursery
THE word parasite brings to mind horror and sci-fi movies, or thoughts of worms, ticks, and leeches. Miram Webster defines them as “an organism living in, on, or with another organism in order to obtain nutrients, grow, or multiply often in a state that directly or indirectly harms the host.”
In our modern, anthropocentric world, we view the parasites as thieves, but I would argue they are part of a larger community of species, all of whom have something to give and something to take from one another.
Let’s talk about some parasitic plants, how they engage with their hosts, with other species, and how we can learn to appreciate their resourcefulness and connectedness.
Mistletoes
Mistletoes, in the family Loranthaceae, are a classic group of parasitic plants. They grow entirely without soil, using a special root that taps into the bark of their host tree. Mistletoes don’t rely entirely on their host, as they have the ability to photosynthesise, but they obtain their water and nutrients from the host.
A lot of people don’t realise that we have an abundance of mistletoes in our area, some of which, like the Brush Mistletoe (Amylotheca dictyophleba), can grow on a range of rainforest species. Other mistletoes, like the Hoop Pine Mistletoe (Muellerina flexialabastra), will only use very specific species, such as the Hoop Pine, as a host.
These aerial plants attract a whole host of butterflies and nectar-loving birds during the flowering seasons, and many frugivorous birds when they fruit.
The fruit, by the way, is extremely tasty and edible for humans. It contains a seed with a sticky tail that allows it to stick to branches after going through a bird’s digestive tract.
During times of flood, fire, or other disturbances, it can become very dangerous for the mistletoes. Many trees will shed limbs in times of drought or other stresses, which will remove the mistletoes if they become too much. In this way, the host tree balances the benefits of added biodiversity and fertility with the cost of hosting mistletoes.
Dodder Vines
Another parasitic plant is the Dodder Vine (Cassytha and Cuscuta species), all of which have edible fruit. There is also a non-native species which is invasive, especially in agricultural settings.
Dodder vines are often yellow, and are leafless, twining vines which attach to other plants using tiny suckers. They forgo photosynthesis and can form dense nets over the edges of forests, providing incredible habitat for small birds and reptiles.
The native Dodders are not so aggressive as to completely smother an ecosystem, and their dense netting provides a shaded and fertile nursery for younger, slower-growing trees to begin germinating.
Like most vines, they chase the sunlight and quickly colonise newly disturbed areas. This can appear destructive at first, but is actually nature’s way of quickly covering up exposed soil from sunlight and erosion.
Parasitic Trees and Shrubs
There are some trees and shrubs which are also parasitic. Relatives of the Desert Quandong (Santalum acuminatum), like the Scrub Cherry (Exocarpus latifolius) or the Native Cherry (Exocarpus cupressiformis), can be found in our areas.
These ancient plants parasitise a bit of energy and water from the roots of all the plants around them. They have been used as food, and for their incredible timber, from ancient times.
I hope you’ve learned something about parasites today which has changed your mind a little on them.
Come visit Mooloolah River Landcare Nursery if you want to see some mistletoes which we have grown in our gardens.
