I know which type you mean, Greg! Guy at the U.S. Botanical Gardens in DC told me that with that kind of Euphorbia plant you need to put it on it's side to prune/cut it down because if you do it upright, the white sap that oozes out will drip down itself and can kill itself. Which is why you got to tip it over so that sap drips onto floor or newspaper or on yourself.
