Spurge (Euphorbia) Family
The Spurge family has 300 genera and more than 5000 species They are mainly tropical but the family includes the genus Euphorbia (2000 species) which has some species common to Britain and the Mediterranean. Called spurge because they were used as purgatives, the stems often have milky juice. Euphorbia have flowers in the form of a cyathium. Linnaeus gave the name Euphorbia to the genus in honour of the Greek physician Euphorbos who died in 23 AD and described one species that was used as a laxative. Dog’s Mercury and the Castor Oil plant are also in this family.
Euphorbia flowers have no sepals and no petals. Each flower has a cyathium at its centre. This is a cup-shaped vessel from which a female flower protrudes but which also houses 4 male flowers, each consisting of a filament and an anther. In this photo there are 3 flowers – one in the centre surrounded by a large bract and 2 on the outside, each surrounded by a smaller bract. In the central flower the photo shows a female flower protruding from the 3mm tall cyathium, on the rim of which sit 4 oval glands (in this species the glands have horns).
A stalk which extends outside the cyathium bears the single female flower – which has an ovary of 5 fused carpels with 5 styles with bi-lobed stigmas. This flower is in the female phase. The female flower’s styles and stigmas are exposed. The male flowers are hidden inside the tube of the cyathium which is seen end-on. The glands secrete nectar, which is then easily accessed by insects such as flies and wasps. The female flower is fertile before the male anthers appear, thus ensuring cross pollination.