Pollen grains from a variety of common plants:
sunflower (Helianthus annuus), morning glory (Ipomea purpurea),
hollyhock (Sildalcea malviflora), lily (Lilium auratum), primrose
(Oenothera fruticosa), and castor bean (Ricinus communis''). ''
Pollen is a fine powder consisted of microspores (pollen grains), which are the male gametes of higher plants. Pollen is produced in the microsporangium (antherss of an angiosperm flower). Pollen grains come in a wide variety of shapes, sizes, and surface markings characteristic of the species (see photomicrograph at right). Most, but certainly not all, are spherical. Pollen grains of pines, firs, and spruces are winged. The smallest pollen grain, that of the Forget-me-not plant (Myosotis sp.), is around 6 μm (0.006 mm) in diameter. The study of pollen is called Palynology and is highly useful in paleontology, archeology, and forensics.
Allergy to pollen is called hay fever. Generally pollens that cause allergies are those of anemophilous (literally wind-loving) plants, which produce very lightweight pollen grains in great quantities for wind dispersal, and subsequently contacting human nasal passages through breathing. Anemophilous plants generally have inconspicuous flowers. Entomophilous (literally insect-loving) plants produce pollen which is relatively heavy and sticky, for dispersal by insect pollinators.
Honeybee carrying pellet of pollen in its corbicula
Pollen is sold as a nutritional supplement, marketed as "bee pollen" (even though it is of course from flowers).