I had a great Father’s Day!
Let me share with you the results of a wander around the outskirts of Kuarka Dorla, the Wadawurrung name for the town I call home. I pay respects to Wadawurrung elders past, present, and emerging.
Grasstrees (Xanthorrhoea australis) line the walking track
Firstly though, I’ve got an itch, can I just jump right into some technical stuff?
*puts glasses on*
An increase in the photoperiod since the southern hemisphere winter equinox on the 21st June, in combination with the resulting increase in temperature has stimulated our angiosperm autotrophic friends to commence flowering and produce an inflorescence.
Phew, thanks, just had to let that out!
Let’s do a slow translation.
If you’re reading this then you’re probably already a fan of the colourful displays that plants adorn themselves with, flowers! Thus making them irresistibly attractive to their pollinating insect partners, who by the way are also very amusing to observe in their various missions at this time of year. They also become irresistible for naturalists and their photo-taking habits.
A European Honey Bee (Apis mellifera) gathers pollen and in turn pollinates grasstree flowers. A Bull Ant (Myrmecia sp.) carries some sand away from the nest.
The reason all this happens is one of the great stories of our planet, and as a species, we’ve finally got a lot of it figured out. Contemplating this incredible planetary cycle is worth doing occasionally, lets have a quick go here, starting with some astrophysics.
It starts with the wonderful situation we find ourselves in as we take a 365.24 days long journey around Sol, tilted on an angle that fluctuates around 23 degrees from the north/south axis. Being on such a tilt creates our seasons, with differing daylight hours and dramatic differences in temperature, as one hemisphere receives increased solar irradiance compared to the other.
Waxlip Orchids (Caladenia major)
Currently accepted theory suggests the tilt was created by an impact of unimaginable force, billions of years ago, knocking Earth onto an angle and also creating that epic satellite, Luna, our Moon!
Without that massive axis-rocking impact, the whole earth would have no seasons, with consistent 12 hour days the whole year-round. Lacking a moon we would have no tides and a dearth of romantic poetry.
Which is a bit sad and boring hey.
Leafless Bitter Pea (Daviesia brevifolia) & Horny Cone Bush (Isopogon ceratophyllus)
Austalia's floral emblem, Golden Wattle (Acacia pycnantha)
Life has responded to this seasonal change in environmental conditions in amazing ways, so let’s jump centuries’ worth of learning and details here about the formation of Earth and astronomy, and head towards my favourite subject, evolutionary biology!
Plants developed the means to harness energy from the sun (autotrophy) quite early on in multicellular life’s history, about 470 million years ago. Mostly it was about cones and spores back then.
It wasn’t until relatively recently, just a cool 130 million years ago, flowers appear on Earth (Angiospermae) facilitating an amazing increase in diversity and increased ability to spread flowery genes across the landscape. An important change happens at the winter equinox. We reach a point in our journey around the sun where the angle of the light hitting our planet, from this brilliant local star, changes the light period of our days from getting shorter to getting longer (photoperiod).
Yeah, yeah, I could have just said 'days' get longer or shorter and you would have known what I meant, but a day is 24 hours to me, a full earth rotation, and that doesn’t change much throughout the year.
Honeybrown Beetle larvae (Ecnolagria grandis) busy skeletonizing that fallen Eucalyptus leaf, into this:
An increase in daylight hours means higher temperatures, and together these are the stimulation needed by many plants to begin flowering (producing a flowering stem with multiple flowers is called an inflorescence - thus finishing the translations of technical jargon in our initial science sentence).
Waxlip Orchid, with bud(dy)...
Bluebeard Orchid (Pheladenia deformis)
Heart-lipped Spider Orchid (Caladenia cardiochila)
In many areas of this world, plant species variety is extreme. Such places include the Amazon, South Africa’s Cape, and Kuarka Dorla heathland. This time of year it is exciting in the southern hemisphere when these areas begin to flower. My backyard of low-lying heath becomes awash with all the colour I hope you have been enjoying.
An unusually wonky flowering spike of the Austral Grasstree
So here we go - at last - back to Father’s Day and our walk through the heath, admiring the flowers in the context of an ancient story of planetary formation and plant evolution.
Or just having fun jumping over puddles.
Writing and photography by Pete Crowcroft, environmental educator for the Great Ocean Road Coast and Parks Authority and GSB organiser (@possumpete iNaturalist, @possum_pete on Instagram)
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