Far more than a garden interloper, this flowering plant reveals itself as a quiet triumph in adaptive design — a botanical marvel whose conservation tells a story of resilience, rarity and ecological intelligence.
I know many well-intentioned gardeners to have waged war on Oxalis — the diminutive, jazzy-coloured sorrel that creeps into terracotta pots, nestles itself between paving stones with unnerving determination and, uninvited, can make itself rather comfortable in a flowerbed. What if this so-called weed is a remarkable and underappreciated members of our native flora?
One of the better-known incarnations of the genus, Oxalis pes-caprae, the yellow daisy-like flower we call ‘sour flowers’ or ‘suurings’ is the stuff of childhood summers, plucked by sticky fingers and sucked for its tart, lemony flavour like nature’s sherbet dip. What we didn’t know is that this is only one of well over 200 species, and the true Oxalis legacy in the Cape Floristic Region is more like a haute couture collection — rare, intricately tailored and breathtakingly diverse. Each autumn, these bulb-bearing beauties wake from summer dormancy and erupt in a parade of leaf forms and flower hues — some blushing pink, others clad in deep fuchsia, pale gold or snowdrop white.
Their bulbs are clever things too. Each year, the plant renews itself entirely, shedding its old tunic like a Dior model slipping out of last season’s gown. Count the layers and you can estimate the age of a plant. Even the smallest bulb might have persisted for decades underground, and because Oxalis can spread clonally — a strategy that enables the plant to duplicate itself without seed when needed — flowering Oxalis patches can be centuries old. Their unique bulbs are just one of a suite of fascinating adaptations to ensure their survival and diversity. Each generation of Oxalis can jump distances, thanks to seed capsules that open with explosive force, catapulting seeds meters away from parent plants.
Oxalis seed also carry beneficial bacteria — microscopic allies that convert nitrogen from the air into nourishing plant food. ‘It’s an extraordinary evolutionary advantage,’ says Oxalis expert, Professor Léanne Dreyer of Stellenbosch University, who has dedicated nearly 30 years to collecting and conserving the plants. ‘They’re perfectly adapted to the nitrogen poor soils of the Cape — it’s genius, really.’ At the heart of the Oxalis floral renaissance, is the Stellenbosch University Botanical Garden. Professor Dreyer’s collection here is the largest in the world — a kaleidoscopic display of more than 180 Oxalis species. For Dreyer, these plants are not just pretty, they’re essential. ‘South Africa’s unique plant biodiversity is under pressure,’ she says. ‘Oxalis might seem small and ordinary, but many of its species are incredibly rare — and some exist only in tiny remnants of natural habitat. If we don’t protect them now, we could lose them forever.’
In her collection, you’ll find Oxalis fragilis, a plant once presumed extinct. Through a collaborative effort of botanists and conservationists, it has been resurrected and multiplied through meticulous hand-pollination. Thanks to the careful stewardship at Stellenbosch University Botanical Garden, the genetic line of Oxalis fragilis and so many other rare and unique Oxalis species are being safeguarded for preservation and future wild reintroduction.
