Benjamin J Kaiser 
Pollen [PDF ebook] 
Structure, Types and Effects

Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes (sperm cells). Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the female cone of coniferous plants. When pollen lands on a compatible pistil of flowering plants, it germinates and produces a pollen tube that transfers the sperm to the ovule of a receptive ovary. Among other topics, this book reviews research on pollen biology and the hybridization process in walnuts, modern conception on the structure and development of the sunflower anther; the role of anion channels in pollen germination and tube growth.