bild

False-colour scanning electron micrograph (SEM) of a pollen grain from Timothy grass, ^IPhleum ^I^Ipratense^i. The wind-borne pollen grains of this species are known to cause hay fever. The grain is seen here in its dessicated form; it would appear spherical if seen ^Iin situ^i on the anther. Magnification: x570 at 35mm, x1100 at 6x7cm, x4000 at 8x10 inch size. False colour has been added by a photographic process called Colorvir. (KEYSTONE/SCIENCE PHOTO LIBRARY/DR. JEREMY BURGESS/SCIENCE PHOTO LIBRARY.)