Size
Pollen grains vary in shape, coloration and size. The smallest grain of pollen belongs to the alpine forget-me-not, measuring three micrometers. The largest is from the cucumber flower, measuring at around 200 microns.
Significance
The size of a grain of pollen is an important piece of information when trying to determine what species of plant it comes from. Tracking down this information is particularly important for those suffering from hay fever or extreme bouts of allergies.
Considerations
Even the largest grain of pollen, at 200 microns, is far too small to study with the naked eye. Microscopes are needed to see the exact shape and characteristics of a pollen grain. Most require about a 10 times magnification zoom, but for smaller grains a 40 times magnification zoom may be needed.