Sporopollenin, making up the exine or outer shell of pollen grains, is the most inert organic compound known, resisting both chemical and physical forces as well as decay. That means it makes great fossils for millions of years, and resistant to enzymatic digestion so that it is still present in bee feces (as well as human feces). It can resist UV radiation and temperatures up to 300C. Pollen grains have been used to study the diet of the Iceman.
Pollen comes in a variety of colours, from yellow (willow), orange (dandelion), grey (fireweed), or even purple (thistle), but most pollen is yellow.
Most pollen grains range between 20-30 micrometers, but the smallest angiosperm pollen is 5 microns, while the largest terrestrial angiosperm pollen is 350 (Cymbopetalum odoratissimum). The marine angiosperm Zostera marina has tubular pollen exceeding 2,500 micros in length and 3-4 microns in diameter. Amphibolis has tubular pollen exceeding up to 5 mm!
Wind dispersed pollen tends to be smooth and simple, while animal dispersed pollen tends to be highly structured, sculptured, rough, or spiny.
The majority of dicotyledons produce pollen grains with three furrows and three pores: tricolporate.
The pollen of some gymnosperms has little balloons attached to it to help it float. They look like Mickey Mouse.
Pollen has antibacterial properties, and in fact “extracts of Prosopis pollen can produce a reactive zone against Staphylococcus aureus (MRSA), in which commercial antibiotics have no effect; Prosopis pollen extracts thus gave better results than those produced by antibiotics like Netromycin and Vancomycin” (Agashe and Caulton, 2009).
Pollen is 7-40% protein, 1.5-3% fat, 7-12% carbohydrate, and 2.8-10.6% minerals (Agashe and Caulton, 2009).
Honey contaminated with Lasiosiphon pollen is toxic.
Pollen has been identified up to 1,000 km from its plant source.