At the end of winter in 2019 I embarked on an expedition to document the carnivorous plants of Western Australia. Over 17 days, I drove almost 3,500 km and photographed over 50 species in their habitat.
With the morning slipping away, we rushed back to the car and embarked on the 250 km journey to the southern town of Walpole. On today’s itinerary was a dozen promising roadside stops I had identified from satellite images, which I hoped would allow us to efficiently survey a range of locations whilst saving precious time.
The first half of the drive was mostly through agricultural land and we passed it at speed. It was just after midday when we reached our first site, a roadside swamp surrounded by jarrah woodland. The large form of D. rosulata grew in the wetter ditches whilst only meters away in the drier forest we found D. collina. This rosetted species is closely related to D. erythrorhiza but can be distinguished by its larger, elongated and more numerous leaves. In the transition zone between the swamp and forest we also sighted D. macrantha with its long hairy stem that scrambles on the surrounding vegetation.
Forging forward, we soon reached the expansive national parks for which the South West region is renowned. Here, high winter rainfall supports the growth of towering karri trees that flourish in vast swathes of forest. Millenia of weathering and geologic uplift has exposed the granite bedrock, forming outcrops that punctuate the surrounding bushland. As we turned a corner, the dense canopy suddenly opened, and we were confronted with a massive rock covering the area of a sports field and rising some two stories high. Stained green with cyanobacteria and covered with a thick layer of moss, the exposed surface of the granite was the perfect location for carnivorous plants to grow.
With excitement, I approached its base and immediately noticed thousands of pink flowers emerging from the wettest patches of moss. These were the blooms of Utricularia multifida, an annual species of bladderwort that races to mature and set seed within a single season. I rushed onto the surface of the outcrop where curious red tufts sprouting out of the moss caught my eye. Upon closer inspection, I noticed that they were D. macrantha which, in the absence of a perch to attach to, were windswept into tight balls. On the forested boundaries of the rock, I found long stems of D. erythrogyne, which reached almost 3 metres in length, and D. aff. pallida “South coast form” scrambling up through the bushes. The former species is distinguished from the latter by a light green coloration and preference for wetter environments. At the other end of the scale, seedlings of D. modesta, with its tiny shield-shaped leaves and wiry stem, grew only a few centimetres tall. I was simply amazed at how much diversity a single outcrop could hold.
After stopping at a few more similar sites, we journeyed closer to the coast where the ecosystem changed from tall shaded karri forest to the exposed low-lying profile of coastal heath. The granite outcrops here were generally more eroded and flatter in profile, and every location we searched seemed to host a different set of carnivorous plants. At most sites, we found plentiful D. erythrorhiza growing in deeper patches of loamy moss and in cracks within the rock surfaces. In contrast to the bright green specimens I had seen in Bunbury, the plants in this region were small and tinged with red. D. glanduligera, an annual rosetted species, grew widely amongst the moss. This interesting sundew has a fringe of long ‘snap’ tentacles which quickly reflex inwards when touched by an insect, effectively catapulting its prey into the sticky centre of its leaves. At a single site, I sighted a small form of D. huegelii. The erect species is characterised by a slender stem and dangling leaves, which I thought had a rather uncanny resemblance to jellyfish.
As the sun set, we finally reached the village of Walpole on the south coast, exhausted but content with a very long day of exploration.