Ragweed pollen. Colored Scanning Electron Micrograph (SEM) of pollen grains on the stigma of a ragweed plant Ambrosia sp. The grains of pollen (yellow) have a spiked surface appearance. The multi-lobed stigma is green. Ambrosia is a daisy like flower which grows in bare and waste ground. Its pollen is windborne and released in great quantities for cross pollination. Ambrosia pollen acts as an allergen causing hay fever (pollenosis) in allergic individuals. Sufferers produce a sensitive antibody which is found on the surface of cells in the nose and eyes; the antibody reacts to the pollen and the nose, throat and eyes become inflamed. Magnification: x150 at 5x7cm size.