For some time I’ve wondered if Ficus brachypoda was new to Central Australia, if aborigines had moved this species there. Brachypoda is an odd fit to the Central Australian landscape. It seems to be the relative of an east coast species, like rubiginosa or obliqua, yet there it is in the middle of a semi arid zone.
It is possible this species is a rainforest remnant, somehow surviving in this region even though all the other rainforest species have long died out and you will hear this story. I’m not too sure this is true.
Allocasuarina and Eucalyptus are prominent examples of plants that evolved from the Gondwanic forests as the region dried. Eucalyptus pollen has been dated to around 25 million years ago so there’s a chance the region has been covered in dry forest for many millions of years. On the other there’s also a chance the region retained its rainforests until the arrival of people and regular burning of the bush. No one knows for sure.
Either way if brachypoda has been in this region since Gondwanic times it should appear more closely related to the other figs of the region. Of the local figs, Ficus atricha, which grows to the north, is the most similar in appearance to brachypoda, yet the east coast species rubiginosa and obiqua are more similar to brachypoda.
The other rock figs of Central Australia have evolved to suit their environments. Platypoda, subpuberula, lilliputiana, etc, are all distinctly different to the east coast species. If brachypoda is a long time resident of Central Australia then why did it not evolve to be different to the east coast figs?
Some collections of hairy leaf figs have been labelled as brachypoda. From what I’ve seen, these plants are not brachypoda. If there are hairy leaf brachypoda, or any variation of brachypoda did exist, it could suggest brachypoda did evolve in situ. There just don’t seem to be any closely related plants near by? The brachypoda populations at Ulurra and 500 km away in Simpsons Gap, seem to me to be the same plant. Separated by 500km I would think these populations should have diverged at least a bit?
Brachypoda seems to interbred with east coast figs. I have some brachypoda in Sydney, they’ve set ripe fruit even though their pollinating wasps live two thousand km away. The pollinator is probably from obliqua, I’ve had fruit on obliqua and brachypoda at the same time so the pollinator could easily be shared. The seedlings seem to have obliqua like features.
When travelling through Central Australia I found brachypoda to be quiet rare. About 50 plants grow on Uluru, I then drove all the way to Alice Springs before seeing another brachypoda. The next major population (I believe) is at Karlu Karlu (Devil’s Marbles) an 11 hour drive from Uluru. Does brachypoda only grown in places that attracted gatherings of people? Did aborigines spread seed from an east coast fig through out the populated areas of Central Australia?