#muellerina

7,050 views  Dec 20, 2019  Mistletoes are woody, parasitic plants that parasitise above ground on branches, as opposed to in the soil. There are almost 100 species of mistletoe in Australia and all of them are native – none is introduced.   But ask most people about mistletoe, and they’ll either recall an archaic tradition involving kissing and Christmas or say it’s a parasite that kills its host tree.  So then why would the City of Melbourne willingly introduce 800 mistletoe seeds into perfectly healthy street trees?

Mistletoe expert Professor David Watson has been involved in the project and says it’s not in the mistletoe’s interest to kill its host. The Melbourne city plan was to try to make the existing trees more wildlife-friendly. By introducing mistletoes, they are bringing structure, food and shelter for a whole range of wildlife.

The project introduced 800 mistletoe seeds from one particular species of mistletoe into a number of Melbourne’s ubiquitous, non-native London plane trees, which are excellent for tolerating pollution and a range of weather conditions, but which are not particularly good as wildlife habitat or food.

The mistletoe plants bring nectar, leaves, fruit, and a dense, evergreen network of branches to nest in. Mistletoes bring these extra ‘resources’ because they are not bound by the same rules as other plants; they take the water and nutrients they need from the tree so they can flower whenever they want, they don’t drop their leaves in times of drought, and so can offer nectar and fruit when no other plants do.

The Melbourne trees have been seeded with creeping mistletoe (Muellerina eucalyptoides), which were chosen because they are slow growing and will easily adapt to plane trees. The two-year-old plant that David points out to Millie still only has a few leaves. The sticky fresh seed was pressed onto the underside of the branch – where any moisture is likely to gather –then the team waited for them to grow. In nature, the seeds are usually distributed by mistletoe birds (Dicaeum hirundinaceum), which only feed on mistletoe fruit. The seeds pass through their digestive system in only 14-15 minutes and, because the seeds are sticky, the birds have to wipe them off on a branch to dislodge them.

Mistletoes also provide a benefit to their host plant; their leaves are very high in potassium and, unlike regular plants that withdraw nutrients from leaves before dropping them, mistletoe leaves are dropped ‘intact’, so the leaf litter makes good, fertile compost. “They are returning most of the nutrients to the tree,” David says.

As its scientific name suggests, creeping mistletoe (Muellerina eucalyptoides), has leaves that resemble Eucalyptus trees – this is to blend in with the natural hosts. Other mistletoes resemble specific hosts, such as acacias, hakeas, banksias, casuarinas, paperbarks and leopardwoods.

While many mistletoes carry their flowers high in a tall tree, it’s worth taking a close look if you see flowers at head height, as they are quite exquisite.

So if you find some mistletoe seed and you’d like to boost the biodiversity of your backyard, try adding some parasitic bling to your tree.

Featured plants: Fleshy mistletoe (Amyema miraculosa) – long, dark red flowers that hang between long grey-green leaves. Brush mistletoe (Amylotheca dictyophleba) – sprays of brick red flowers with pale green tips and wide, dark green glossy leaves. Samphire mistletoe (Amyema microphylla) – stubby, cylindrical fleshy leaves Wireleaf mistletoe (Amyema preissii) – thin, wiry bright green leaves, bright red drooping flower bunches and white or pinkish-white berries Creeping mistletoe (Muellerina eucalyptoides) – Eucalypt-shaped leaves and long, green, hanging flower buds that open to reveal red stamens inside. Leopardwood mistletoe (Amyema lucasii) – Attractive blue-green foliage with bunches of bright yellow flowers. West Australian Christmas tree (Nuytsia floribunda) – the tallest mistletoe plant, which grows directly in the ground as a tall tree – it can reach 15m tall – but whose roots attach to the roots of nearby plants to access nutrients. Has brilliant golden-yellow flowers.

I was in Melbourne for most of the last week, which wasn’t ideal for spotting new species since I barely left the CBD the entire time. That said, I did spot these mistletoes growing in the London Plane trees along Flinders Street outside our apartment, which was quite surprising - I’ve never seen native mistletoes growing on exotic trees before, and actually getting established on the trees seemed unlikely since there’s no native bushland nearby for birds to bring the seeds from. Mistletoe fruit passes through a bird in well under an hour, and emerges so sticky that the bird has to physically wipe its arse on the branch to get them off - which, of course, is exactly what the mistletoe wants. 

So I did some digging, and it turns out there was a project in 2018 by ecologist Lee Harrison, to plant 800 mistletoe seeds in street trees around the inner city and CBD. 

He had good reason to, as well - the foliage, flowers and fruit of mistletoes is highly desirable to a range of species, and if all the mistletoes are removed from an area the bird diversity can drop by a third. David Watson of Charles Sturt University has described that experiment as "one of the strongest described effects of what's called a keystone species — one that has a disproportionate influence on the ecosystem."