Comprehension Passage
Pollen grains, which vary in size, shape, color, and design across species, are generally spherical. They have a distinctive two-layered wall. Pollen grains consist of two cells. Pollen formation begins with microsporogenesis. Pollen can trigger severe allergic reactions, such as asthma.
Parthenium or carrot grass that came into India with imported :
1
Rice
2
Maize
3
Wheat
4
Sugarcane