For self-proclaimed ‘gum nuts’ this is eucalyptus heaven

There are 1013 known species of eucalypt. Dean Nicolle has planted 980 of them.

This incredible collection of gum diversity is at the Currency Creek Arboretum, which sits between the wine-growing regions of Mclaren Vale and Langhorne Creek in South Australia. Nicolle, a eucalypt botanist, arborist and ecologist, and his partner Annett Boerner, who is a geoecologist and scientific publications specialist, maintain the arboretum themselves and open it to the public a couple of times a year.

There were about 50 of us gathered at a recent open day: some self-confessed gum nuts if their t-shirts were to be believed; others looking for advice on planting large properties or small gardens. The rest of us were there to learn a bit more about the trees that dominate our landscape – from the alps to the arid interior, dry river beds to sweaty tropics.

All the plants in the Currency Creek Arboretum are grown from seeds collected in the wild. Nicolle collects from just one tree per species, and usually plants out four individuals from the seed that germinates. This gives the most accurate picture of natural variation, as all the trees of the planted species share the same mother.

The trees are planted in rows; this isn’t a garden, but more like a zoo, where you get to marvel at highlights from widely disparate geographical zones. For researchers, this is an incredible resource, and Currency Creek Arboretum has already generated 140 scientific papers. For visitors, it’s an awe-inspiring journey through eucalypt habits.

Here’s the world’s smallest eucalypt, the varnished gum, E. vernicosa, which makes a round, spreading shrub to about a metre tall, and comes from the cold, wet west coast of Tasmania, and takes its name from its shiny leaves. While known as a pot plant in Europe, it’s not commercially available here. Yet.

Up the hill is the stunning lobe-fruited mallee, E. pressiana, from Western Australia, which forms a multi-stemmed shrub to a couple of metres with clusters of yellow flowers and very handsome fruits. Nicolle reckons it has potential to be grown more widely, including in Sydney’s well-drained areas.

And why grow crepe myrtle, he says, when you could grow E. diversifolia, the coastal mallee. Lipstick red buds open to creamy flowers; birds and insects go nuts.