Pollen Source is a term used to describe the source of pollen, which is a powdery substance released by plants for reproduction. Ragweed (7 letters) is a type of plant that produces large amounts of pollen and is a common allergen. STAMEN (6 letters) is the male reproductive organ of a flower, which produces and releases pollen. Sporesac (8 letters) is a sac-like structure found in some plants that contains spores, which are small reproductive cells that can develop into new plants.