An art historian suggests that Botticelli's famous "Venus and Mars," an homage to the power of love, may actually have a hidden psychedelic message. Art historian David Bellingham of Sotheby’s Institute of Art suggests that the plant clutched by the satyr in the bottom right corner is actually Datura stramonium, a poisonous hallucinogen. From the Times:
“This fruit is being offered to the viewer, so it is meant to be significant,” he told The Times. “Botticelli does use plants symbolically. In the background are laurel [bushes], for example, which are a reference to his patrons, the Medicis. Datura is known in America as poor man’s acid, and the symptoms of it seem to be there in the male figure. It makes you feel disinhibited and hot, so it makes you want to take your clothes off. It also makes you swoon.”Mr Bellingham believes the 15th-century painting was intended not only as a depiction of Venus and Mars but also of Adam and Eve. He believes that the Datura may represent the fruit from the Tree of Knowledge that Eve offered to Adam, triggering their ejection from the Garden of Eden. The fruit is commonly depicted as an apple, but was not specified as such in the Bible. "Botticelli’s painting Venus and Mars may allude to sex and drugs" (via The Daily Grail)
Personally I've closely observed the Botticelli's painting and the plant depicted by the Italian artist doesn't seem at all to fit with the actual Datura stramonium plant, in particular with its leaves, absolutely irregular and extremely toothed (see below). Bellingham's hypothesis is not convincing, at least to me and for what concerns stramonium (maybe another species of datura?)
Datura stramonium, also known by the popular names 'jimson weed' and 'thorn apple', isn't considered an entheogen/psychedelic, but rather a 'deliriogen', a plant which induces a (often unpleasant and even dangerous) state of delirium.
(click on Botticelli's picture to biggify and see details)