Color enhanced scanning electron micrograph of pollen from the Mexican (Aztec) marigold (Tagetes erecta). This marigold is native to Mexico and Central America, yet it is often called the African marigold. This plant has been used since prehispanic times for medicinal purposes. Natural phytochemicals that include sulfur-containing rings (thiophenes), are most probably the active ingredients, which kill gram-negative and gram-positive bacteria in vitro. The flower petals have been used in other foods to add color and flavor, including poultry feed to ensure a good coloration of egg yolks and broiler skin. Nowadays, T. erecta is grown to extract lutein, a common yellow/orange food color (E161b). Image width: 233 micrometers. Magnification: 430x if printed 10 cm wide.