How do cacti and African euphorbias show convergent evolution?

Cacti and African euphorbias provide a classic example of convergent evolution, a process where unrelated or distantly related species independently develop similar traits to adapt to comparable environmental niches.12

Although they belong to entirely different plant families, many species of New World cacti and African euphorbias have evolved to look remarkably alike. Both groups have adapted to arid, desert conditions by developing succulent, water-storing tissues, spiny exteriors, and reduced or absent leaves to minimize water loss. These shared physical characteristics are not the result of common ancestry but are instead independent evolutionary responses to the severe challenges of living in dry environments.234

Despite these morphological similarities, the two groups remain distinct in their biological makeup. A key difference is that euphorbias typically possess a milky, often poisonous sap, whereas cacti do not. Additionally, their reproductive structures differ significantly; for instance, euphorbias feature unique floral structures known as cyathia, which are quite distinct from the flowers of cacti.3