Last seen in 1804, Psoralea cataracta was rediscovered by Brian du Preez, a PhD student in botany at the University of Cape Town, when he accidently stumbled upon a population on a narrow track close to a river on a farm near Tulbagh in the Western Cape. Photo: Wiida Fourie
Flanked by a landscape of mountains, the picturesque Tulbagh in the Winelands of the Western Cape has proven to not just be a great tourist attraction, but an area which has for several decades harboured one of the world’s rarest plants.
Last seen in 1804, Psoralea cataracta was rediscovered by Brian du Preez, a PhD student in botany at the University of Cape Town, when he accidently stumbled upon a population on a narrow track close to a river on a farm near Tulbagh in the Western Cape. Photo: Wiida Fourie
When ardent mountain climber and botanist Brian du Preez recently ascended the Winterhoek Mountains – north of Tulbagh – in search of the Indigofera (true Indigo) species for his PhD, little did he expect to stumble upon the extinct Psoralea cataracta (‘fountain bush’) – one of the first recorded plant species to have been lost to forestry and agriculture in the Western Cape in the 1800s.
Until now, Psoralea cataracta was only known from a single specimen collected from the Tulbagh waterfall in 1804.
The delicate flower and thread-like flower stalks of Psoralea cataracta, a type of fountain bush which only occur close to mountain streams in the Tulbagh region of the Western Cape, last observed in 1804. Picture: Brian du Preez
After years of fruitless searches, it was officially declared extinct in the Red Data List of South African Plants.
But with professor Charles Stirton, a United Kingdom-based world-renowned specialist on the genus Psoralea having confirmed the rediscovery as the long-lost species last seen in 1804, Du Preez has now made history – something likely to stimulate more interest and further research on the plant species.
Excited about his rare find, Du Preez told The Citizen: “As soon as I saw those delicate thread-like flower stalks, I knew it was Psoralea cataracta. After having immediately recognised the plant species in the field, my joy would be more comparable to how I felt when we won the Rugby World Cup.
The delicate flower and thread-like flower stalks of Psoralea cataracta, a type of fountain bush which only occur close to mountain streams in the Tulbagh region of the Western Cape, last observed in 1804. Picture: Brian du Preez
“The rediscovered extinct Psoralea cataracta is a type of fountain bush from the pea family that used to grow next to mountain streams in the Tulbagh region. At present, we do not know the importance of the species in the broader ecology of the area, because this is yet to be studied. The fact that it was rediscovered after being classified as extinct – not having been seen since 1804 – is extremely special.
“Legumes in general – and we presume it would be in this case too – are pioneer plants in fynbos vegetation.”
Professor Stirton said: “This is a very important find as 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 are slim.
“Well done to Brian for a wonderful find.”
Custodians of Rare and Endangered Wildflowers (Crew) project manager Ismail Ebrahim said: “It is really uncommon to find a properly extinct species – something that hasn’t been seen for ages.
“With Cape Flora, it is even harder because most species are restricted to a really small patch and it is easy to miss them if you don’t go off the beaten path.
“This illustrates the value of proper field botany – as they did it in the olden days.”
The Winterhoek mountains, said Du Preez, are “an extremely a beautiful range, with steep high sandstone peaks and shale soils on the lower slopes”.
The delicate flower and thread-like flower stalks of Psoralea cataracta, a type of fountain bush which only occur close to mountain streams in the Tulbagh region of the Western Cape, last observed in 1804. Picture: Brian du Preez
“The plant diversity is amazing and there is a proliferation of indigenous legumes currently painting the mountain bright yellow in patches.
“The area also has a number of spectacular waterfalls,” he said.
Asked what he planned to do to ensure Psoralea cataracta was protected from extinction, Du Preez said: “We are currently doing field work to determine species population in the area by establishing how many plants there are.
“We have already informed the South African National Biodiversity Institute (SANBI) for a conservation assessment so that the plant is protected by law.
“The land owner has also been informed of the importance of the plant species on his farm.”
The 26-year-old Du Preez is building up quite a reputation for finding long lost species.
As a BSc Honours 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.
In 2017, he completed an MSc at Stellenbosch on Polhillia.
This year has also seen Du Preez collecting a new species of Aspalathus, growing on sand dunes on the banks of the Riet River in the Swartruggens Mountains north of Ceres.
He now wants to get the species defined, due to that part of the Riet River being earmarked for orchard expansion.
Du Preez: “We can only conserve what we have described. Only species formally described can receive a Red Data List status, to be legally protected from development – depending on conservation status.”
For this reason, Du Preez has decided to tackle a revision of the genus Indigofera in the Greater Cape Floristic Region for his PhD. The diverse genus comprises over 100 species in the region, with at least 30 new species to be formally described.
With his bakkie, he has for the past six months been covering thousands of kilometres – from the Richtersveld through to the Eastern Cape, already having collected over 60 Indigofera species.
Last seen in 1804, Psoralea cataracta was rediscovered by Brian du Preez, a PhD student in botany at the University of Cape Town, when he accidently stumbled upon a population on a narrow track close to a river on a farm near Tulbagh in the Western Cape. Photo: Wiida Fourie
For botanists, the period from September to November every year is when most plants are in flower. Next week, he is off on a three-week field trip to the Garden Route and the Eastern Cape.
“When in the field, I typically spend at least four to six hours a day – sometimes as much as 10 hours per day,” said Du Preez of his plant excursions.
On his passion for plants, he said: “It started from a young age. I had a vegetable garden going at primary school, as well as growing indigenous trees to sell at the school market or in my parents’ coffee shop.
“My passion for botany really developed in 2012 when we had to learn 100 indigenous tree names for a university module.
“My lecturer noticed my talents and encouraged me to get involved with citizen science via iSpot – now moved over to iNaturalist.
“I also joined our local Crew group called the Outramps, and started hiking in the mountains with them to monitor rare and endangered plant species on a voluntary basis for SANBI.”
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