Johannesburg - It’s a rare feat that few young botany students can claim: rediscovering three presumed extinct plant species.
That’s what Brian du Preez, a PhD student in botany at UCT, has achieved.
He attributes his knack for finding long-lost species to his “sharp eyes” and keen knowledge of legumes in the Greater Cape Floristic Region (GCFR).
The 26-year-old recently rediscovered a type of fountain bush (psoralea cataracta) from the sweet pea family, one of the first recorded species to have been lost to forestry and agriculture in the Western Cape in the 1800s.
P. cataracta, see picture left, found close to mountain streams in the Tulbagh region,
was known only from a single specimen collected from a Tulbagh waterfall in 1804.
In 2008, after many futile searches, the species was declared extinct on the Red Data List of South African Plants.
Du Preez, while doing fieldwork for his PhD in the Winterhoek Mountains north of Tulbagh, accidentally stumbled on a population on a narrow track close to a river on a farm. From previous search efforts as a volunteer with the Custodians of Rare and Endangered Wildflowers (Crew) around the waterfall, he immediately knew what a remarkable find it was.
“As soon as I saw those delicate thread-like flower stalks, I knew it was Psoralea cataracta. I was overjoyed.”
While a BSc honour’s student in botany at Stellenbosch University in 2016, Du Preez rediscovered two presumed extinct species in the pea family, Polhillia ignota and Aspalathus cordicarpa, last seen in 1928 and the 1950s, respectively. He went on to complete an MSc on Polhillia in 2017 at SU.
This year, he collected a new species of Aspalathus growing on sand dunes on the banks of the Riet River in the Swartruggens Mountains, north of Ceres. He is now rushing to get the species described, as the river area is earmarked for orchard expansion.
Of his ease in finding vanished species, Du Preez said: “I have sharp eyes when it comes to spotting legumes in the field. The fact that I have rediscovered three presumed extinct species (all legumes) comes down to knowing the plant family.”
Professor Charles Stirton, a specialist on the genus Psoralea and Du Preez’s co-supervisor, hails it as a wonderful, important find. “It shows how the Cape is still relatively unexplored in many mountainous areas.
“Given that many of the Cape flora only come up briefly after fires, fading quickly and that sometimes these fires are irregular, the chances of being in an area at the right time is slim.”
Ismail Ebrahim, project manager at Crew, agreed. “It’s really uncommon to find a properly extinct species, something that hasn’t been seen for ages.
“And with Cape Flora it is even harder, because most species are restricted to a really small patch and it’s easy to miss them if you don’t go off the beaten path.”
Du Preez said the species faced few threats. “I’ve found plants growing in three spots now. Population sizes vary from a few dozen to several hundred. It will have lost a lot of habitat and numbers to farming activities on the lower slopes in that area, but most of the populations I’ve seen grow in steep valleys where they cannot plough.
“Future threats include alien
invasive species that are starting to spread in some streams in the area, but this can be managed if action is taken speedily.”
Local farmers will be encouraged
to safeguard the areas where the
plants grow.
Humans are damaging South Africa’s precious biodiversity, often unwittingly, he believes. “Relationships exist between all species that allow life to thrive and maintain very high species diversity in areas such as the GCFR.
“If one species is lost, several other species may also go extinct due to their dependence on that one species. This is particularly the case with insects, many of which are not even known to science, but contribute greatly to the maintenance of our healthy ecosystems,” said Du Preez.
Conserving landscapes, not single species, is key.
“Once you conserve a landscape, you conserve all living creatures within that landscape, from the largest plants and animals to the smallest of insects.”
South Africa needs to be more worried about the spread of invasive alien plant species “as these are fast becoming the biggest threat to our biodiversity heading into the future”.