[Campbell Biology P.880] If flowers had shorter styles, pollen tubes would more easily reach... | Practice Question

If flowers had shorter styles, pollen tubes would more easily reach the embryo sac. Given this, what is a plausible evolutionary explanation for the development of very long styles in most species of flowering plants?

  • A: Long styles increase the efficiency of self-pollination, ensuring reproductive success.
  • B: Long styles serve as a more effective barrier against undesirable or incompatible pollen, promoting selective fertilization.
  • C: Longer styles are primarily for structural support of larger anthers.
  • D: Long styles enhance water absorption from the atmosphere, aiding pollen tube growth.

Explanation

The 'WHAT IF?' question implies that shorter styles would make pollen tube growth easier. Therefore, long styles must confer some evolutionary advantage that outweighs the difficulty of pollen tube growth. A key function of the style, especially a long one, is to act as a selective filter, ensuring that only compatible or desirable pollen grains reach the ovules for fertilization. This mechanism helps prevent inbreeding or fertilization by pollen from different species, promoting the fitness of the offspring.