The genus is botanically connected by their unique flowers. These are tiny, petal-less and grouped into clusters of one female to many males; these are then surrounded by leafy bracts.
Another common characteristic is the milky latex which, being held under pressure, oozes out when the plant is cut or wounded.
This sticky sap has been used historically as a purgative, hence the common name spurge, (espurgier is an old French word meaning to purge). This latex is, however, poisonous and contact should be avoided.
One Euphorbia I particularly like the form of is the tree spurge, Euphorbia dendroides - dendron being Greek for tree. It slowly matures into a rounded shrub up to 2m high with a thick trunk and woody branches.
It can be seen growing at Dunedin Botanic Garden in the bed beside Lindsay Creek in the rock garden.
Native to the coastal Mediterranean in rocky habitats, it therefore grows well in full sun with very good drainage, and will withstand drought once established.
• Robyn Freeth is the rock, water and alpine collection curator at Dunedin Botanic Garden.
