'Heaven on Earth' in a botanist's garden
- Friday 15 January 2016 2:10PM
- Tim Entwisle
Following six years in London, botanist Steve Hopper returned to the granite coastline of south-western Australian to settle on the edge of a global biodiversity hotspot. He takesTim Entwisle on a tour of his garden.
King George Sound, in the far south-west corner of Australia, is where English explorer Captain George Vancouver landed in 1791. A decade later Matthew Flinders anchored in the same bay, along with botanist Robert Brown and gardener Peter Goode, who took the opportunity to collect 500 or so plants. It was their first taste of the exotic (to them) Australian flora.
Today King George Sound is where botanist Steve Hopper lives with his wife Chris, in a small hamlet behind Goode Beach, surrounded by peppermint woodland and within earshot of the surf.
We have a responsibility to look after plants in our gardens and stop them escaping.STEVE HOPPER, BOTANIST
Hopper has only recently returned to Australia following a six-year stint as head of the best known botanic garden on the planet, Royal Botanic Gardens Kew, in London.
Before that he was director of Kings Park and Botanic Garden in Perth. For 40 years, in between running botanic gardens and other roles, he has studied the diverse and spectacular flora of Western Australia.
He says it was the plants, country and family that drew him back to Western Australia. 'This is like heaven on Earth for someone interested in field biology,' he says. 'It sits on the edge of a global biodiversity hotspot.'
We are 400 kilometres south-west of Perth, on a granite coastline. Hopper likes granite, particularly the plants that grow in and around the ephemeral pools that form in large blocks of granitic rock. He also has a passion for understanding how Aboriginal people have lived in these landscapes, and what we might learn from them.
The garden and house at Goode Beach were already established when the Hoppers moved here a few years ago. Most of the garden plants were Australian natives, with a few exotics suited to the local climate, such as heathland plants from South Africa.
Natural coastal vegetation laps around the fence, including dense thickets of coast sword-sedge (Lepidosperma gladiatum) which the local Noongar people use to make twine for binding. 'If you pull gently on the leaves, it has a white leaf base that you can chew on,' Hopper says. 'It tastes like coconut.' Even a marshy sedgeland has its uses.
As in most parts of Australia, invasive plants are a problem. 'Parts of Albany look more like Cape Town than Australia,' he says. 'We have a responsibility to look after plants in our gardens and stop them escaping.'
In his own garden, a bright orange flowered plant from South Africa called soldier boys (Lachenalia) is 'quietly going feral' in his front yard. Steve is ready to suppress its expansion should it look like jumping the fence. Of the native plants, Hopper mentions the pin-cushion hakea (Hakea laurina), which birds and honey possums love. They have placed a bird bath nearby so the honey eaters, all 15 species, can feed, wash and feel secure when they visit the garden.
There's a local pigface (Carpobrotus edulis), endemic to the south-west, with purple-pink daisy-like flowers. Pigface is a fire suppressant and is easy to grow. Its common name is Hottentot fig, borrowed from a South African species, which in turn was labelled by Europeans who came up with Hottentot as their best attempt at a local language designation. If you peel back the skin from the mature red fruits, you find a fig-like inner core that tastes pleasantly sweet and salty.
'A million years ago or so, the ancestors of Carpobrotus edulis lobbed into Australia from South Africa, and we now have half a dozen endemic species here,' Hopper says.
It's the kangaroo paws (Anigozanthos), however, that feed Hopper's mind. Soon after he arrived in Goode Beach he bought seven species from the Friends of Kings Park in Perth. He wanted to return to a conundrum he first tackled 40 years ago in his PhD study on the classification, biology and ecology of this genus.
It was relaxing science. Every morning for two months Hopper sat in his living room and recorded how and when the flowers were visited by local birds. There are two main types of Anigozanthos: those with short stems, often called cat's paw or catspaw, and those with long stems or scapes, the 'true' kangaroo paw. The Western Australian floral emblem is one of the tall ones, a red and green flowered kangaroo paw, Anigozanthos manglesii. All are visited and pollinated by honeyeaters, standing on the ground to feed from the cat's paw and perched on the stem to reach the kangaroo paw flowers.
Hopper found that the red wattlebirds flitter around almost exclusively at ground level when the cat's paws are peaking, then swap to perching on stems, hopping or flying to the next, when the species with taller stems are in full bloom.
In a sense, Hopper says, the plants have worked out how they can get as much of their pollen as possible to a flower of the same species. This means there is more cross-pollination and more chance to adapt and remain competitive in a changing environment. It also makes it easier for the wattlebirds to get food, saving energy by only having to stay at one level.
You get this same kind of pattern, and the mutual evolution of plants and animals, with prostrate banksias and grevilleas. So even though the number of different pollinators is limited in Western Australia, there can be mechanisms that encourage plant species to favour particular floral attributes.
That's just one reason why the flora is so diverse in south-west Western Australia. Another is that the south-west is what Steve calls an OCBIL—an old climatically buffered and infertile landscape. OCBILs are scattered around Australia and other parts of the world, mostly in the Southern Hemisphere. Much of the Northern Hemisphere is post-glacial, with the plants and animals we see today only able to return 18,000 years or so ago.
Australia, on the other hand, has been mostly exposed and glacier-free for some 250 million years. The last volcanos were about 130 million years ago and oceans have surrounded the continent for 90 million years. Over many millions of years rain has left the soils infertile, placing another pressure on plants and animals to adapt and in the process evolve more species. This aggressive evolution continues around Goode Beach and elsewhere in Australia, but it's in the south-west corner where we find the greatest diversity of species.
Hopper says south-west Western Australia has such biodiversity not only because there are more species evolving, but because there are fewer being lost. In fact, there is good evidence that what we call 'speciation' (the generation of new species) occurs at the same rate in western and eastern Australia. In the east, for some reason, more go extinct. To understand why, perhaps we need to spend more time in our gardens.
A gardening show with a twist. Talking Plants is a witty and at times provocative discussion show on all things botanical.