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“How many colours
are there in a fieldof grass to the
crawling babyunaware of green?”
algae, the slug does not
have to eat again for the
rest of its life. All it has to do
is sunbathe”.
By 2018, populations of
this slug in the wild had shrunk
to the point where they were
becoming “too rare to research”.
But green pigments are surprisingly
rare in the animal world. Even among
birds, only a handful sport features of a true
green – most green feathers arise through a
combination of blue structural colouration
and yellow carotenoids. One exception is
turacoverdin, a unique copper pigment that
generates bright green plumage in several
birds from theMusophagidaefamily, most
notably the turaco. The birds accumulate
copper through the fruits, flowers, buds and
other plants of their diet. It’s not known if
turacos have especially copper-rich diets,
or are better at extracting copper from their
foods.
Some of the greensoutside my window
come from casuarina, dianella, dietes,
Alpinia caerulea. Since the rupture of this
continent’s landscape after 1788, many of
these plants have worn names that speak
more of the northern hemisphere – she-
oaks, lillies, ginger, iris – the linguistic
component of what the historian,
geographer and biologist Alfred W Crosby
has described as the attempted creation
here of a “neo-Europe”. The “foreign
aspects of Australia’s nature and
ecology caused many Europeans
to react by imposing their
own plants and animals in
order to ‘improve’ the
land,” writes Lucinda
Janson in her account
of imperial settlement
and expansion in
early colonial NSW.
Theirs was often
a “confused and
defensive reaction
to an ecology and
a way of living
in a land very
different from their
own”. To homesick
British colonials
such as Barron Field,
this country’s coloura circle with 11 green squares and one blue
as a circle with 12burusquares.CHLOROPHYLL, one of the fundamental
ingredients for photosynthesis, is what
gives a plant its green. This nourishing
process converts light into sustenance for
vegetation – it’s one of the fundamental
mechanisms of life, of growth.
As early as 1704, Isaac Newton
suspected a link between light and growth
in hisOptiks, suggesting that “gross Bodies
and light [were] convertible into one
another”. He meant this in a more alchemical
than biological sense: that magical thinking
that would give us the power to transform
one material into another. But work by
researchers in the subsequent years of the
18th century – including Joseph Priestley
and Antoine Lavoisier – led to Jean
Senebier’s 1782 deduction that green
plants “breathe in” carbon dioxide from the
air and “breathe out” oxygen, all through
their interactions with sunlight.
The “basic equation” of photosynthesis,
a process by which “a green plant
illuminated by sunlight takes in carbon
dioxide and water and converts them
into organic material and oxygen”, was
confirmed by work published by Nicolas
de Saussure in 1804.
An alchemy all of its own.
Perhaps one of the most beautifully
symbiotic uses of chlorophyll comes from
the small green sea slugElysia chlorotica– a
marine opisthobranch gastropod known not
only “for kidnapping the photosynthesising
organelles and some genes from algae” but
for retaining these in working order for the
slug’s year-long lifespan.
In 2010, this slug was found to have
“acquired enough stolen goods” to generate
the complete “plant chemical-machine
pathway work inside an animal body”,
according to researchers at the University
of South Florida in Tampa. It raised the
possibility, in the words of one zoologist,
of “branch tips touching” in the tree of
life. And in a poetic twist, the slug itself
resembles a delicate green leaf – as if it is
embodying the plants whose mechanisms it
now mimics.
It was also found that “once a young slug
has slurped its first chloroplast meal from
one of its few favoured species ofVaucheriaThe sacoglossan sea slugElysia
chlorotica, above, eats algae
and incorporates its ability to
photosynthesise; in a different
kind of absorption, a turaco, below,
displays its copper-toned sheen.