Rubber, cassava, castor oil and poinsettias all come from the spurge family
The spurge family gives us natural rubber, the staple root cassava and the Christmas poinsettia, yet it is also stocked with poisons, from the ricin in castor seeds to a mangrove sap that can temporarily blind. Some African members have even evolved to look almost exactly like cacti.
With about 7,500 species in 300 genera, Euphorbiaceae is the fifth-largest family of flowering plants. Most are herbs, but tropical members include shrubs and trees such as the Para rubber tree, and succulent species like Euphorbia canariensis have converged on a cactus look. The family lives on every continent except Antarctica, with the greatest variety in the tropics. One of its oldest fossils, a mineralised fruit from India, dates to around 66 million years ago, the very end of the Cretaceous.
Its flowers are always single-sexed, with male and female ones typically on one plant. Euphorbia itself goes further, bundling a ring of single-stamen male flowers and one central female flower into a cup of fused bracts and nectar glands called a cyathium, a fake flower that passes for a real one. Many fruits split into three or more chambers that burst open to fling their seeds.
Chemistry is the family's calling card. Two subfamilies ooze milky latex, harmless in one and poisonous in the other; the rubber tree's latex is the main source of natural rubber, while the white mangrove's causes blisters and, in the eyes, temporary blindness, earning it the name blind-your-eye. Cassava roots contain cyanide-forming compounds. Although various species appear in traditional medicine, no rigorous clinical evidence shows euphorbia extracts treat any disease.
Molecular studies have produced surprises, showing that Rafflesiaceae, the family of parasitic plants that includes giant-flowered rafflesias, arose from within the spurges. Useful members include the Barbados nut and the garden croton, while leafy spurge and Chinese tallow have become invasive weeds in North America. Several Euphorbia species, such as E. appariciana and E. gymnoclada, now face extinction.
Source: Euphorbiaceae
