Which is a feature of the life cycle of flowering seed plants, but not a feature of the life cycle of nonflowering seed plants?

Flowering seed plants often use insects to transfer pollen from one flower to another. Nonflowering seed plants, such as conifers, generally rely on wind for pollination. Both groups have alternation of generations, and neither has a dominant gametophyte; flowering plants are also characterized by double fertilization, not single fertilization. Thus, insect pollination is the distinguishing feature.

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