The Kruger to Canyons Biosphere Region has long been recognised as one of South Africa’s most ecologically significant landscapes. Now, this richly biodiverse region has added a remarkable chapter to its conservation story with the rediscovery and protection of a rare plant species – likely new to science, found only in the Blyde River Canyon.

  This rare species belongs to the genus Thorncroftia, a lesser-known cousin of the more familiar Plectranthus, and is endemic to a narrow range within the Blyde River Canyon area. Characterised by striking purple and pink flowers and a distinctive floral structure, Thorncroftia species typically flower at the end of summer, lighting up the rocky hillsides where they grow.

From forgotten specimen to scientific curiosity

  The story begins in 1954, when renowned botanist Dr Leslie Codd collected a specimen near Mariepskop, of what he then believed to be Plectranthus succulentus. Years later, in 1961, Codd reclassified it as part of the Thorncroftia genus, though no further sightings were confirmed. For decades, the plant’s fate remained a mystery.

  The landscape surrounding Mariepskop changed dramatically in the decades that followed. The natural mosaic of grasslands and forest patches was replaced by commercial pine plantations from the mid-1960’s, followed by decades of abandonment and infestation by invasive alien trees. By the time negotiations to incorporate these degraded slopes into the Blyde River Canyon Nature Reserve began in the 1990’s, much of the native vegetation, and the ecological balance it supported, had been lost.

Restoration clears the way for hope

  It was only in recent years that the Kruger to Canyons Biosphere (K2C), through its Catchment Restoration work, began rehabilitating the area. Systematic alien clearing, particularly of invasive pine and gum trees, was carried out by local teams as part of broader landscape restoration efforts, and this critical intervention created conditions conducive for the return of indigenous plant life.

  In September 2024, Professor Kevin Balkwill, together with K2C Project Manager Simon Attwood and the Mpumalanga and Limpopo Plant Specialist Group, retraced Dr Codd’s steps using historic herbarium records and aerial imagery. Although the original collection site had been heavily affected by landslides and pine growth, the team’s persistence paid off. Against the odds, a few Thorncroftia plants were found clinging to life atop boulders on a slope where pines had been recently cleared.

  If these alien trees had remained, the endemic plant would almost certainly have been shaded out or chemically suppressed by pine litter – a phenomenon known as allelopathy. Thanks to the restoration work, light and resources were once again available for indigenous flora to thrive.