Final answer:
Flagellated sperm of ground pines necessitate water for fertilization, as it allows the sperm to swim towards and fertilize the egg within a moist environment.
Step-by-step explanation:
Because the sperm of ground pines are flagellated, water is required for fertilization. In seedless vascular plants like ground pines, water acts as a medium for the flagellated sperm to reach the egg. These plants, which include club mosses and ferns, depend on a moist environment for successful fertilization because the sperm must swim to encounter and fertilize the egg.
The reproductive strategy of sperm swimming in moisture is a trait observed in other bryophytes as well. Bryophytes rely on external water sources, like dew or rainwater, for the male gametophyte's sperm to reach the female gametophyte's egg. Even though evolution has led to the development of pollen tubes in seed-producing plants, which does not require water for fertilization, flagellated sperm in plants like ground pines and bryophytes still necessitate a watery medium for successful fertilization.