Madwoman's Milk

The morning was spent out on a farm near Thorney, recording plants. Having driven through fog, the day settled into that sort of damp, penetrating greyness that eastern Britain can do so well. Despite it being so late in the year, lots of species were still flowering and I recorded over 140 species from my allocated area.

One of the highlights was finding a very large population of dwarf spurge Euphorbia exigua growing in a field of sugar beet. This delicate species has declined significantly on recent years and is now considered a Near Threatened species in the UK. It was growing with this rather more showy sun spurge Euphorbia helioscopa, also known as Madwoman's Milk because of the white latex which exudes when the stems are cut.

All flowers in the Euphorbiaceae are unisexual (either male or female only), and they are often very small in size. In Euphorbia, the flowers are reduced even more and then aggregated into an inflorescence or cluster of flowers known as a "cyathium". This feature is present in every species of the genus but nowhere else in the plant kingdom.

The main defining feature of the cyathium is the floral envelope or involucre that surrounds each group of flowers. The involucre almost always has one or more special glands attached to it, most often on the upper rim, and these glands and their appendages vary greatly in size and shape - they are quite rounded in the sun spurge. There may be specialized leaves called cyathophylls or cyathial leaves that surround the cyathium and give an overall flower-like appearance to the whole complex inflorescence.

Inside the involucre are the flowers, usually with a number of extremely simplified male flowers consisting of a single anther, filament, and pedicel. Generally there is a single female flower consisting of a pedicel, a three-parted ovary, and no petals or sepals associated with it.

The milky sap or latex of spurges is suggested to have a protective and defensive role in helping heal wounds and in deterring potential plant-eaters It contains a wide variety of chemical compounds and some of them are toxic and potentially carcinogenic. Compounds known as terpene esters are common and often account for the extremely caustic and irritating properties of the milky sap, either by direct contact with the skin or even by exposure to the air and inflammation of the eyes or mucous membranes. A plant to treat with respect!