Around 215 species, commonly called milkweeds, are from the genus Asclepias. They are tuberous perennials or subshrubs, sometimes evergreen and typically grown for their intricate flowers. They are comparable to orchids in their flower complexity and have an unusual pollination system. The name milkweed comes from the latex they exude from their stems - milky-white in colour and toxic in most species. The name silkweed refers to the spindle-shaped seed pods that emerge after flowering. This genus contains species which are attractive to insects, providing nectar to bees, wasps and other insects. Originally from South Africa and North and South America, some require dry conditions, others wet. Ideal for a bright border, wildflower garden or under glass in cool climates.