Final answer:
Pollen is the major structure besides seeds that reduces a plant's reliance on water for reproduction.
Step-by-step explanation:
Pollen is the major structure besides seeds that diminishes a plant's reliance on water for reproduction. Pollen grains carry the male gametes of the plant and can travel far from the plant that produced them, spreading the plant's genes and avoiding competition with other plants. With the protective coat preventing desiccation and mechanical damage, pollen grains reduce the need for water for fertilization.