The New Student's Reference Work/Pollen

Pol′len, the microspores of seed-plants. Pollen is developed within pollen-sacs, which occur on the anthers of stamens. Each pollen-grain is an asexual spore, consisting of a single cell, which has an outer heavy and more or less modified wall, known as the exine, and a delicate inner wall, known as the intine. Pollen-grains are often variously marked, sculptured and even winged by the modifications of the exine. Certain pollen-grains, as those of the mallows, are covered with conspicuous spiny points, and this family may be recognized by its pollen. Pollen has often been mistaken as the equivalent of a male cell, being spoken of as the male element. It should be distinctly understood that pollen grains are microspores and that microspores are asexual spores. When the pollen germinates, as other spores do, it produces a male gametophyte, as do all microspores. It is in connection with this new plantlet or male gametophyte that the sperms are developed.