Viability of pollen grains:-

• Viability of pollen grains of some cereals (rice, wheat, etc.) is 30 minutes. Some members of Leguminoseae, Rosaceae, & Solanaceae have viability for months.
• Pollen grains of some plants (e.g. Parthenium or carrot grass) are allergic for some people. It leads to chronic respiratory disorders – asthma, bronchitis, etc.