ASDM Digital Library for Kids!

The 8000 worldwide species of spurges are as ecologically diverse as the composites. They occupy most habitats and exhibit nearly every growth form used by plants. In fact, annuals, perennials, trees, succulents, C₃, C₄, and CAM species can all be found in the single genus Euphorbia. Until recently this genus contained the little weedy spurges in our gardens, the spectacular Christmas poinsettia (which originated in tropical Mexico), and African succulents — some of which are nearly perfect mimics of the New World cacti. Now some taxonomists raise many of our species previously in a subgenus Chamaesyce to the genus Chamaesyce.

Recognizing such a diverse family by vegetative characteristics is virtually impossible. In most species the inflorescence is a cyathium, a single female flower with its distinctive three-lobed ovary surrounded by a number of male flowers consisting of a single stamen each. The male cyathia may have colorful bracts that resemble petals (e.g., crown of thorns — Euphorbia milii), and some species have colored leaves that serve the same function (e.g., poinsettia, Euphorbia pulcherrima). In some species male and female flowers are borne on separate plants. A few genera produce more typical flowers with true sepals and petals. The poinsettia is one of the largest ornamental nursery crops; tens of millions are produced annually for the Christmas season. Other economically important examples include manihot (the source of cassava and tapioca) and castor bean (the source of the once-popular health remedy, castor oil).