Euphorbia poissonii, also known as Euphorbia poissoni  and, incorrectly as Euphorbia poisoni is a highly irritant and toxic succulent member of the large and varied spurge family of plants. It is native to northern Nigeria, where local farmers extract its latex for use as a pesticide. Its powerfully irritant and pain-producing nature mandates use as a fencing plant.
It is named for French botanist Henri Louis Poisson, who formally described other Euphorbia species.
In addition to a variety of irritant phorbol-type esters, the latex contains resiniferatoxin and tinyatoxin, two closely related highly irritant resiniferonol-type esters. The most active toxin, resiniferatoxin, binds to pain receptors in the same way as capsaicin but much more powerfully. It stimulates the neurons to fire repeatedly, causing pain.