Last year I posted about a brangle between a Little Wattlebird and a Blue-faced Honeyeater in Noosa. This was one image, now differently cropped to show the object of the conflict – a banksia flower, half-hidden in foliage.
To a casual observer – though clearly not to the two birds - the attraction of a banksia is not so obvious. Many banksia trees have ugly gnarled shapes, and rugged irregular bark, like this one:
And of course the Banksia Men were the baddies in May Gibbs children’s books. They were based on old dead banksia cones like the one shown near the end of this post. Gibbs’ images are still under copyright, so I’ve attempted my own version!
However for many nectar-eating birds and mammals, Banksia = Beautiful or = Bountiful. The distinctive flowering cones are laden with pollen and copious amounts of nectar. The ripe seeds are a bonus for some birds, too.
This is a budding cone early in its development:
At first I found it hard to relate one of these cones to more usual flower structures with anthers and stamens. I discovered that the banksia is fairly typical of Proteaceae flowers, and their structure is more easily illustrated using these grevillea flowers:
Each flower has a stigma (female) at the end of a long red style. The style begins tightly curled inside the pinkish-white perianth – four united sepals - visible on the unopened flowers on the right. The opening flowers are in the middle (in the central flower, you can see the yet-to-emerge stigma in the light shining through the perianth.) On the upper left are two fully open flowers, with their stigmas at the end of the straightened styles. The anthers (male) at the tips of the perianth aren’t visible here as the latter remains tightly curled.
The Banksia integrifolia or Coast Banksia flower cone consists of several hundred flowers (or florets) all tightly packed together on a hidden stem. As the cone develops, the pale green colour shown in the earlier photo changes to cream. Compared with the grevillea sample, the styles and perianths are more elongated, like this:
Looking more closely, you can make out the individual perianth tips covering the tips of the styles like little helmets:
Even at this stage the flowers are already bearing nectar, as this Red Wattlebird knows:
When the flowers are fully open, with the stigmas fully exposed, they look like this:
In the close-up view, you can see the stigmas at the tip of the styles, and what seems like a tangle of perianths curled up at their base. The greyish structure at the upper mid-left appears to be a perianth that failed to open properly.
When the flower cone dies, any fertilised ovaries at the base of the style will develop into full-blown seed follicles – visible here as green half-moons protruding from the cone. This particular cone has also been attacked by Gall Wasps (Mesostoa), which are responsible for the yellow outgrowths on the right:
The seed follicles become dry and woody, as do any remaining styles and perianths. By this time the honeyeaters are long gone, and the specialised seed-eaters now take over. This is a Yellow-tailed Black Cockatoo feeding on the seeds embedded in a cone:
Close up, you can see the cockatoo’s tongue extracting the seed from its follicle, surrounded by the woody remains of the styles, each with its stigma at the tip. Several other seed follicles are also visible.
The previous flower/seed cone is from a Banksia serrata or Old Man Banksia tree, easily recognised by the serrated edges to its leaves. The seed cones need a bushfire to release their seeds from the follicles, and the resultant blackened cone with its gaping follicle-covers is the prototype Big Bad Banksia Man!
Flowering banksia cones vary in colour. The Old Man Banksia’s cone is greyish:
My favourite cone is the golden one of the Heath Banksia (Banksia ericifolia). This is a photo I took back in 2013:
Perhaps banksias aren’t so bad or ugly after all!