The Pollination Story; part 2, getting noticed

This series started recently here, with the beginnings of the great pollination partnership between flowering plants and animals. From early on in the development of the partnership, competition was strong between neighbouring plant species for the services of the insects that were already being trained to associate the flowers' scents and 'flags' - petals and sepals - with an energy reward. How to be more noticeable? A very simple one is for flowers to be held high over a low-growing plant.

Silky Swainson-Pea Swainsona sericea Fabaceae, south of Canberra, a threatened species.
The flowers are waved high above the ground-clinging foliage.

Another way of course is to have huge flowers, but that's pretty risky - a single flower can be damaged by weather or by animals interested in eating it rather than seeking its nectar. A better solution is to have lots of little flowers clustered; such a cluster can last a long time by having successive flowers open over a period of time, and the loss of individual flowers is of no moment. Here are some common Australian examples, but you'll know of plenty of equivalents, wherever you live.

Firewood Banksia Banksia menziesii, Badgingarra NP, Western Australia.
As with many flower spikes, the hundreds of flowers here are opening from the base - the top half
of the spike presently comprises buds.

Rose Banjine Pimelea rosea, Cape le Grande NP, Western Australia.

Raspberry Jam Tree Acacia acuminata, Christmas Rock Nature Reserve, Western Australia.
In wattles the true nature of the flower balls or spikes is best seen in the buds, before the
numerous stamens hide the individual tiny flowers.
(The common name is from the astonishing scent of the cut wood.)

Candles Stackhousia monogyna Stackhousiaceae, Canberra.
A very common spring flower round here; the spikes are far more obvious than the individual small flowers.

The most familiar such clusters of flowers however are found in the daisies. The 'basic' daisy flower is a cluster of hundreds of tiny florets growing from a common base.

Billy Button Craspedia sp., Namadgi National Park, above Canberra.

However many other daisies have taken this sleight of hand a step further by adding 'petals', often in contrasting colours, around the head of florets. These 'petals' are in fact sterile florets whose sole purpose is to draw attention to the fertile disc florets.

Olearia tenuifolia, Mount Tennent, south of Canberra.
The purple sterile ray florets contrast dramatically with the fertile yellow disc florets.

Yet other daisies utilise colourful papery bracts - modified leaves - instead of ray florets to make the tiny disc florets more conspicuous.

Alpine Paper Daisy Xerochrysum subundulatum, Kosciuszko National Park, New South Wales.
The bracts are stiff and shiny (hence the common name).

Other unrelated plant groups have arrived independently at the same solution, with often dramatic results.

Flannel Flower Actinotus helianthus Apiaceae, Pilliga NP, New South Wales.
Here the tiny flowers can be clearly made out if the picture is enlarged, surrounded by
soft 'flannel-like' bracts.

Waratah Telopea speciosissima Proteaceae, Budderoo NP, New South Wales.
Like the related banksias, waratahs have numerous clustered flowers (though seated on a flat
disc rather a spike), but have gone further, with the big red leafy bracts to make them even more obvious.
(This is the state flower of New South Wales.)

Royal Hakea Hakea victoriae Proteaceae, Fitzgerald River NP, Western Australia.
This is an amazing plant, growing metres high in the heathland (see below); the small white flowers (here
represented by the woody fruits) are hidden down among the leathery cabbage-sized leaves,
whose bright colours draw attention to them.

Royal Hakeas in the landscape, Fitzgerald River NP.
The species only grows in this park, one of the most botanically diverse places on earth.

So far we've looked at multiple flowers - inflorescences - but I'll end today with a couple of examples of single flowers which have taken unusual evolutionary steps to become more visible.

Pigface Carpabrotus sp., Kalbarri NP, Western Australia.
The fertile stamens are in the centre of the flowers. There are no true petals - the numerous 'false petals'
are staminodes, sterile structures derived from stamens which are playing the part of petals to increase visibility.
(The fruiting structure, not seen here, is alleged to resemble a pig's head...)

And lastly, perhaps if we wanted to draw attention to plane flying overhead, we might flash a mirror. It seems that the familiar buttercups, members of an ancient flowering plant group, are doing just that!

Buttercup Ranunculus sp. Tallong, New South Wales.
The shiny petals are due to a layer of reflective subsurface cells.

Next time, we'll explore how individual flowers became more complex, to distinguish themselves from their neighbours of other species.

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