This species occurs naturally(?) from Cape Verde to Japan, although it has so long been cultivated that its particular origin is unknown. It is an evergreen shrub with leathery leaves in whorls on the stem. In nature, it is often found in dry streambeds, and it has been termed a rheophyte (plant that grows in flowing water), even though it does fine under hot, dry conditions1,2.
Widely planted in our southern states for its showy white, yellow, red, or pink flowers, this is also one of the more toxic landscape plants. It contains more than 50 toxic compounds, such as cardiac glycosides (chemicals which influence heart function). Use of the wood for cooking or inhalation of the smoke is dangerous; a single leaf may be potentially lethal1,3.
1 Mabberley, D.J. 1987 The plant-book. Cambridge University Press.
2 Wikipedia: https://en.wikipedia.org/wiki/Nerium (22 July, 2015).
3 Levetin, E., and K. McMahon 2012 Plants & Society. McGraw Hill.