The Tagates Patula or French Marigold, is native to the highlands of Guatemala and Mexico. This showy and reliable annual is a member of the Daisy family (Asteraceae.) The Aztec peoples used marigolds for medicinal and ceremonial purposes, and bred marigolds to create larger and larger blooms. In the 1500's, seeds were taken to Spain and cultivated in monasteries. From there, they were brought to France, and to North Africa where they became naturalized. The dried petals are added (in minute quantities) to chicken feed to enhance the colour of egg yolks. They are also used in small quantities as spicing and colour in some ethnic cuisines.
French Magriolds are considered a premier "companion plant." They produce a toxin, alpha-terthienyl, that kills a large variety of nematodes (tiny worms) that could potentially feed on some roots. However, many nematodes are not only harmless, but beneficial to the soil, eating microscopic life and releasing bacteria to give your peas and beans a boost. In turn, legumes "fix" nitrogen in the soil for other garden vegetables. Do plant marigolds in your vegetable garden - we do! - but keep individual soil requirements for each vegetable in mind.
Many thanks to Delaronde_Hillbillies for giving me this spot to plant a marigold. 