In my last post I wrote about the first month of my PhD experience, about getting all the paperwork in order, about the enormity of planning for the next four years. So what am I actually studying?
In short, orchids and fungus gnats! Yep, fungus gnats. Let me explain.
One of the first orchids I ever saw was what I now know to be Pterostylis nutans, the iconic Nodding Greenhood. It was 2012, and I was a young undergrad naïve to the seductive world of native orchids. We were on a field trip to the NSW south coast as part of a Geobiology course, and happened to walk through a lovely little patch of forest near Potato Point. I think we were on our way to look at a cliff full of fossils, or something like that. As usual, I was loitering at the back of the group when I noticed an odd looking thing.
The first Pterostylis nutans I saw, back in 2012.
At the time I couldn't make head or tail of it; heck, I wasn't even sure it was a flower! No one else in the group seemed interested in the mystery thing, but it made an impression on me and a year later I was hooked on orchids. NOT the boring, epiphytic, run-of-the-mill, flower-shop orchids mind you; the odd, tiny, quirky, impossible to find, downright whacky terrestrial native orchids.
Fast forward to 2015 and I decided to do my Honours on the very rare, Canberra-local spider orchid, Caladenia actensis. When it came to deciding whether to do a PhD and what to study, I felt drawn to return to the greenhoods. In the years since, greenhoods have become probably the favourite orchids of both Ali and I, so it seemed like a natural choice.
One of the exciting things about studying greenhoods is that, despite being one of the largest orchid genera in Australia, there has been very little scientific work on their method of pollination. All greenhoods have an unusual trap system whereby a movable labellum flips backwards upon contact, trapping the insect pollinator in the flower. The unfortunate insect then has to crawl through the flower, getting pollen pasted on its back on the way, before it can escape. But what pollinates the ~300 species of greenhoods? And how are the orchids attracting their pollinators?
The anatomy of Pterostylis chlorogramma. The labellum (the brownish red hairy bit) flips upwards when disturbed, trapping the insect in the hood (the top rounded bit). The insect crawls from right to left inside the hood before it is able to escape.
Enter the fungus gnats. As it so happens, anecdotal observations suggest that greenhood orchids are pollinated by various types of fungus gnats. (Fungus gnats are small to tiny flies which are a nursery pest and very few people care about and/or bother studying). The only confirmation of pollination method in greenhood orchids comes from one species in Western Australia which mimics the sex pheromone of the female fungus gnat to attract males which pollinate the orchid.
So basically I have 300 species of greenhood to choose from, to try and work out how pollination happens. There are many different shapes in the greenhood genus, and some are undoubtedly using different pollinators and pollination methods. My job will be to try and understand the different methods and strategies operating within the greenhoods. Bring on the next 3.5 years!