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
Parthenium hysterophorus production, an additive in manure for biogas production, as a biopesticide, and as green manure and compost. Contact with the plant causes dermatitis and respiratory malfunction in humans, and dermatitis in cattle and domestic animals. The main substance responsible is parthenin, which is dangerously toxic. It also is responsible for bitter milk disease in livestock when their fodder is polluted with "Parthenium" leaves. Among other allelopathic effects of the species, the presence of "Parthenium" pollen grains inhibits fruit set in tomato, brinjal, beans, and a number of other crop plants. Light infestations of "Parthenium hysterophorus" in cultivated fields may be