Nature Diary

REMARKABLE: A dwarf silver wattle, Acacia nanodealbata, one of the rarer plants found in the Wombat Forest. Picture: Russell Best
REMARKABLE: A dwarf silver wattle, Acacia nanodealbata, one of the rarer plants found in the Wombat Forest. Picture: Russell Best

One September a few years ago, I was walking in the bush and was treated to a lovely spectacle – a slow, sunshine drenched fall of snow among the flowering wattles.

The large flakes landed on my dogs’ backs and in my hair. It was like a scene from a romantic film.

With or without snow, the silver wattle flowering is one of my favourite sights each year – hundreds upon hundreds of yellow fluffy flowers set among silvery grey foliage. This splash of rich yellow is then followed closely by the mass flowering of another common wattle, the blackwood. The blackwood has somewhat lighter lemon yellow flowers.

I like to think of wattles as the glue that holds the bush together. Where there are eucalypts, there will be several species of wattle, from the tree-sized silver wattle and majestic blackwood, to the many shrubs, both spiky and soft leaved; and down to the ground, the creeping tiny shrubs that are almost like groundcovers.

Wattles have nitrogen-fixing nodules on their roots, which provide much needed fertility to the low nutrient Ordovician clay or white chalky skeletal soils that are so common under foothill forests.

Wattles are like companion plants to the rest of the bush. 

Wattle foliage is a prized food source for many different types of insect – ants, beetles, butterflies, wasps and bugs. The bark and wood are also riddled with insects.

These insects provide food for bush birds such as thornbills and fantails.

Larger birds such as yellow-tailed black cockatoos can extract wood-boring beetle grubs from the trunks of the bigger wattle species.

Sugar gliders are renowned for eating the soft sweet sap of silver wattles, while the insects and pollen of wattles are an equally important food source.

Blackwoods provide a secluded resting spot for powerful owls during the day. Their dark glossy green foliage creates a bit of privacy and protection from small birds, which may mob the owl.

Wattles will be in full flower for the next month or two, and then the trees will be laden with seed – much loved by crimson rosellas. The wattle seeds are held in pods, and each comes with a little gift, or bribe for ants called an elaiosome.

These are easy to see in blackwood seeds in summer as they are bright orange. Many ant species value the nutrients in the elaiosomes, and carry the seeds back to their nests, so ensuring they are planted in the damp, nutrient rich soil as well taking to the air with seed eating birds.

Most of the wattles flowering now in Trentham, Glenlyon, Daylesford are the silver wattles, Acacia dealbata.

Surprisingly, tucked among the forests of these areas is a relative of the silver wattle – the dwarf silver wattle, Acacia nanodealbata. This small tree looks very much like the silver wattle – but it is only found in Victoria and is classified as rare. The dwarf silver wattle is one of 25 threatened plant species in the Wombat Forest. At first, it is somewhat hard to tell them apart. They both have feathery bipinnate foliage that is silvery in colour, and bright yellow globular flowers at this time of year.

However, once you get your eye in, as they say, you can tell that the leaves of the dwarf silver wattle are smaller, and more densely packed. The whole tree looks a bit more bunched, and less open than the silver wattle.

The dwarf silver wattle is a cool climate, mountain loving species, found in the coldest stretches of the Wombat Forest, on Mount Macedon, in the Otways and in the Healesville/Warburton area.

I lived in the area for more than a decade before Gayle Osborne from Wombat Forestcare took me out to show me stands of this rare species, hiding in plain sight among its more common cousin.  

A photographer in the US has some incredible photographs of ants gathering elaiosomes: see www.alexanderwild.com.

Tanya Loos