The one we all know is Euphorbia pulcherrima, better known as poinsettia. But this is just one member of a family of more than 2000 different species, some of which are perennial, a few are annual; some are grown in the garden, some in the rockery and some as houseplants; some are shrubs; and some are succulents which are sometimes mistaken for cacti; all carry small flowers enclosed in bracts - specialized leaves which are often different from foliage leaves in their colour, shape or size. (The brightly-coloured parts of poinsettias are their bracts; the flowers are tiny and insignificant.)
Originally from southern Europe and south-west Asia, the Euphorbiaceae is possibly the most diverse family of terrestrial plants. The unique characteristic which determines membership of the family is the way in which the plant gathers its very small, unisexual flowers … either male or female … into a cluster called a cyathium, where a number of extremely simple male flowers are usually accompanied by a solitary female flower in the centre. This feature is not found anywhere else in the plant world; and researchers at the Royal Botanic Gardens in Kew have suggested that the genes that normally control features of individual flowers have overlapped into the cyathium itself.
Euphorbia … commonly called spurge … is mentioned by the Roman official Pliny the Elder who, in the year 79 AD, referred to the plant under that name in his encyclopaedia, The Natural History. The Swedish botanist Carl von Linné … the man who formalised the modern system of naming organisms called binomial nomenclature … saw no good reason to find a new name for the family, which his Roman predecessor had named in honour of the Greek physician Euphorbus, who had identified this succulent plant as a powerful laxative. And, intriguingly, the common name ‘spurge’ derives from the Old French word espurgier … itself derived from the Latin expurgare … meaning ’to purge’. And so, gentle reader, it will come as no surprise to learn that the sap has traditionally been used as a purgative, or laxative – although it must have been an unpleasant one to use. Do not try to use it at home!
This poisonous sap, which resembles white latex, “Is collected from incisions made in the fleshy branches, and is so acrid that it burns the fingers,” to quote that eminent authority Mrs. Margaret Grieve, writing in her Modern Herbal, which was first published in 1931. (This amply demonstrates the risk of calling a book the’ modern’ whatever.) She continued, “It flows down the stems and encrusts them as it hardens in the sun. Poor Arabs bring in the resinous masses for sale in Morocco, whence it is chiefly exported from Mogador. The dust is so intensely irritant to the mucous membrane that the mouth and nose of those handling it must be covered by a cloth.” (We know Mogador as Medina of Essaouira.) Pleasant stuff, then, which the plant probably developed as a defensive mechanism to deter herbivorous animals from munching its foliage. It is also likely that the manner in which the sap dries and forms a crust helped heal any wounds sustained by the plant.
The milky sap actually contains a good selection of chemical compounds, some of which are serious irritants if they get into the eyes, nose or mouth. Any latex on the skin should be washed off immediately, for it is insoluble in water after it dries. Even the vapour of the sap can be irritant; and children and pets should be kept well away from any variety of succulent Euphorbia. Yes indeed, Euphorbias are bleeding plants in more ways than one!