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
Daniel Pollen May 1846, Pollen married Jane Henderson, the daughter of an officer of the Royal Navy (Lieutenant Essex, RN, of Demarara). He moved with her to Kawau Island in 1847, after becoming medical officer to a Scottish copper-mining company. Pollen spent several years on Kawau, during which time he began to contribute articles to "The New Zealander" supporting the agitation for responsible government. He was also to the fore in supporting temperance, scientific, and library movements there. When the New Zealand Constitution Act 1852 became law, Pollen was made chief clerk in the Auckland Superintendent's office. From there, he rose through