Cyanide producing plants

A reader asks the Phactor: "I understand some plants, seeds etc. contain cyanide. If ingested and the source of the cyanide is not immediately known, can any test determine the specific source of the poison i.e. it came from apple seeds or peach pits. Or is the chemical compound simply the same no matter what the source?"  
Technically plants do not contain cyanide.  What they do contain are cyanogenic (= cyanide generating) compounds, molecules that when acted upon release cyanide as one of the products.  Cyanogenic compounds are of two types: glycosides (something linked to a glucose) and lipids (fats/oils).  In the case of apple seeds the compound is called amygdalin (a glycoside), and when glucose is removed, what's left (it has a name, but does it matter to you?) forms a molecule of cyanide and another characteristic molecule.  So if this product can be detected, and here we must assume biochemists are clever enough to do so, it would demonstrate that the source of the cyanide was amygdalin, but that could come from a number of different plants (Could be apple or peach seeds, both members of the rose family.). It would limit the suspect list because there are cyanogenic plants that do not have amygdalin.  Glucosides taste bitter, our warning sign of potential toxicity, so sweet almonds (a close relative to peaches and apricots) are not actually so sweet as they are not bitter, indicating their lack of toxicity. The link (above) to the reference is pure biochemistry, but there you go.