Australian Geographic — May-June 2017

94 Australian Geographic

Fortunately, we don’t need much skill at naming smells

to enjoy them or to use them for identification purposes.

Leaves that smell fragrant when crushed declare that a

shrub in heathland or coastal woodland is likely to fall

into one of just four family groups – those of the eucalypts,

citruses, mints or daisies – and knowing that is a boon

to identification.

A large number of plants in these groups have acquired

telling names. There are eucalypts called peppermints or

lemon-scented gums, daisies called curry bushes, kerosene

bushes and the fruit-salad plant.

Smells produced by animals don’t attract as much atten-

tion. Visit a creek on a wet night and any frog-lovers you

find will be using calls to identify these amphibians. How-

ever, noted Australian frog researcher Mike Tyler says they

could be sniffing instead.

“Several frog skin odours are comparable to culinary

herbs, but there are others that are more like curry powder,”

Mike, who is based at the University of Adelaide, explains

in his book Frogs. “In fact, with a little experience of what

different species smell like, a sniff is almost as good as a

glimpse as an aid to identification.”

If we all had a dog-like devotion to olfaction, our field

guides would be telling us that Peron’s tree frog smells of

citrus while the green-and-golden bell frog is reminiscent

of the kitchen herb thyme.

Like plants, some animals use odorous compounds for

defence. Many small snakes and freshwater turtles, when

handled, will smear you with potent-smelling faeces that

make your hands smell awful for an hour or so. Stinkbugs

release their foul smell from glands between their front

pair of legs.

The larvae of swallowtail butterflies absorb aromatic

oils from their food plants and emit them on soft ‘horns’

known as osmeteria, which protrude above their heads

when they’re harassed. Orchard swallowtail caterpillars

smell of citrus and blue triangle butterflies of camphor.

Fungi can surprise us when, in strange shapes and col-

ours, they are summoned by rain from musty earth or

crumbling wood. Their mystique is often enhanced by

curious smells that can recall cucumber, radish, garlic, curry,

aniseed, apricots, pear drops, fresh flour, cedar, cooked

shellfish, urine or ether.

The yellow-staining mushroom (Agaricus xanthodermus),

which looks inviting enough to have caused many

poisonings, would bring less strife if heed was paid to its

disinfectant smell. Stinkhorns smell like sewage or rotten

meat, to attract the flies that spread their spores. Australia

also has plants that trick blowflies into spreading their

pollen, including stinking lilies (Typhonium spp.) in rain-

forest and, in heathland, stinking roger (Hakea denticulata).

If you’re in arid or semi-arid eastern Australia during

wet or humid weather and detect an intriguing whiff of

boiled cabbage, you can be sure that you’re among a stand

of stinking gidgee (Acacia cambagei) trees.

T

HE EASIEST WAY to enjoy wild odours is to crush

and sniff leaves on walks. The sensation can be

dramatic when one anonymous shrub among many

releases a burst of aniseed or lemon.

The effect invites curiosity about the plant’s identity

and the purpose of the smell. There are many plants I greet

after an absence by taking a good sniff, including lemon

myrtle, celerywood and Tasmanian blue gum. For me, their

aromas are central to their identities.

Sniffing vegetation carries little risk, but frogs can be

unsafe. Green tree frogs can bring on nausea if you inhale

their peanut-butter odour for too long. Theirs is another

smell with a story: green tree frogs will rest on your hand

rather than leaping off in fear because they have poison

glands to protect them, announced by their odour. They

smell strongest when stressed.

But many smells remain as mysteries for the keen

observer to explain. Why does Western Australia’s white-

plumed grevillea (Grevillea leucopteris) have flowers that

smell like old socks? And what exactly does the curry

flower (Lysinema ciliatum), also growing in WA, attract to

its spicy-smelling flowers?

Mysteries like these are guaranteed to keep me sniffing

my way through the Australian bush.

Why does WA’s white-plumed

grevillea have f lowers

that smell like old socks?

AG

Shield bugs

and other

stink bugs produce

repulsive odours that

help protect them

by deterring hungry

predators, such as

lizards and birds.

SCIENTIFIC NAME:

Poecilometis

sp.

1