About 12 kms west of Katherine I chanced across what I believe to be a hybrid zone. Originally I stopped to take photo’s of a Ficus racemosa and as always I did a bit of exploring around the tree to see what else was there. It became clear there was something interesting about the figs in this area.
In a 30 square meter area, dry creek beds hosted some scrappy Ficus coronulata, Ficus aculeata and what seemed to be intermediate forms of both. Most exciting were two plants right by the road that were unlike any fig I’d seem before.
At around 2 metres tall and wide, these two shrubs had the fruit of coronulata, some of which had ripened to a deep purple, and soft narrow leaves most similar to Ficus carpentariensis. They were thin, hairless, smooth to touch but not glossy or waxy. Coronulata as an adult has almost glossy long straight to sickle shaped leaves and aculeata rough, round sandpaper leaves. These leaves were almost a meeting in the middle of the features of both species.
The bark and branch structure was like that of coronulata yet the plant’s size seemed be restrained to a shrub by aculeata genes. These plants looked to be coronulata x aculeata and the wide variety of forms of the surrounding figs backed up my impression.
Samples were collected, locations taken etc and 15 different specimens were handed into the Sydney RBG for dna sampling. The hope was to prove these plants had mixed species parents. Sadly the parenting tests never went ahead.
Two years after sowing the seed of these apparent hybrid plants, the one surviving seedling is very much a Ficus aculeata. This was the final bit of proof I needed to confirm these were hybrids, seedlings of hybrid plants will normally revert to look like one of their grand parents, in this case this seedling looked aculeata and nothing like it’s parent which was more like coronulata.
While on the same trip I came across lot’s of variations of aculeata, coronulata and carpentariensis and finding these two hybrid trees made me realise that Ficus carpentariensis plants too are the product of aculeata, coronulata crosses! Ficus carpentariensis hasn’t been widely collected, the few plants I have seen vary quite a bit from each other and always seem to occur in areas where both aculeata and coronulata grow, often right next aculeata. To me carpentariensis plants display intermediate features of both species. In my opinion Ficus carpentariensis is not a true species, more a collection of coronulata and aculeata hybrids.