Tony Heald / Egyptian goose (Alopochen aegyptiaca) pair amongst Devil's-thorn yellow flowers (Tribulus terrestris) Etosha National Park, Namibia, March.

Tony Heald / White-backed vulture (Gyps africanus) sunbathing amongst Devil's-thorn yellow flowers (Tribulus terrestris), Etosha National Park, Namibia, March.

Tony Heald / Klein Okevi waterhole covered by Devil's-thorn yellow flowers (Tribulus terrestris) Etosha National Park, Namibia, March 2016

Tony Heald / Black-faced impala (Aepyceros melampus petersi) young male Lying in Devil's-thorn yellow flowers (Tribulus terrestris) Etosha National Park Namibia, March.

Tony Heald / Black-faced impala (Aepyceros melampus petersi) female leaping above Devil's-thorn yellow flowers (Tribulus terrestris) Etosha National Park, Namibia.

Tony Heald / Lion (Panthera leo) male, walking amongst Devil's-thorn yellow flowers (Tribulus terrestris) Etosha National Park, Namibia.

Richard Du Toit / Dubbeltjie flowers (Tribulus terrestris) with Lion (Panthera leo). Kgalagadi Transfrontier Park, South Africa, February.

Neil Aldridge / White stork (Ciconia ciconia) in grassland, Mapungubwe National Park, South Africa.

Ann & Steve Toon / Ground squirrel (Xerus inauris) feeding in Devil's thorn flowers (Tribulus terrestris) Kgalagadi Transfrontier Park, Northern Cape, South Africa. Non-ex.

Richard Du Toit / Lion (Panthera leo) in Dubbeltjie flower (Tribulus terrestris) Northern Cape Province, South Africa, February.

Albert Lleal / Yellow Vine (Tribulus terrestris) seed covered in sharp spines that enable dispersal, magnification 23x

Richard Du Toit / Red Hartebeest (Alcelaphus caama) feeding on grasses near Yellow Vine (Tribulus terrestris) flowers, Kgalagadi Transfrontier Park, Botswana