Silver fir pollen grains. Coloured scanning electron micrograph (SEM) of pollen grains from the silver fir tree (Abies sp. ). These are wind- borne pollen grains, and have two rounded wings" which enable them to stay in the air. Pollen grains, which carry the male reproductive cells, are released in vast numbers in late spring, and some inevitably land on the female parts of the tree. The silver fir is a common evergreen tree in the mountainous areas of central and eastern Europe. The wood is used in the manufacture of paper, and the leaves of this tree are distilled to produce turpentine. Magnification: x320 at 6x7cm size."