rose pollen grains - closeup view 3d

air allergen allergic allergy asthma autoimmune disease blooming botany cough defense dispersal fertilization fever flowers food germ grain grass hay honey bee immune system inhale itch lung meadow medicals mucous membrane nose particle plant pollen pollination pollinosis reaction reproduction rhinitis season seed sneeze snot spore sporopollenin spring stamen swollen trachea tree gametes