Pollen as large as about 90–100 µm. In angiosperms, during flower development the anther is composed of a mass of cells that appear undifferentiated, except for a partially differentiated dermis. As the flower develops, four groups of sporogenous cells form within the anther. The fertile sporogenous cells are surrounded by layers of sterile cells that grow into the wall of the pollen sac. Some of the cells grow into nutritive cells that supply nutrition for the microspores that form by meiotic division from the sporogenous cells. In a process called microsporogenesis, four haploid microspores are produced from each diploid sporogenous cell
Pollen beetle but pollen is a major part of its diet. Several members of the Nitidulidae are similarly referred to as pollen beetles. In particular, practically all the species in the genus "Meligethes" are called pollen beetles. Of these the most notorious is probably the one now accepted as being properly called "Meligethes aeneus"/"Brassicogethes aeneus". It is called the "Brassica pollen beetle", "Rape pollen beetle" and similar names, because it first became prominent as a pest of such crops in the first quarter of the 20th century. Many species in the family Oedemeridae are similarly called "pollen beetles". For example, the Southern