Complex sentence: Pollinium, or plural pollinia, is a coherent mass of pollen grains in a plant that are the product of only one anther, but are transferred, during pollination, as a single unit.
Split into simpler sentences: Pollinium, or plural pollinia, is a coherent mass of pollen grains in a plant. They are the product of only one anther, but are transferred, during pollination, as a single unit.