Why are the sporophytes of lower vascular plants more conspicuous than their gametophytes?

In the life cycle of lower vascular plants, the sporophyte is the dominant generation, making it the conspicuous plant body typically observed in nature. This dominance is a result of evolutionary trends in which the sporophyte stage has progressively increased in size and complexity, while the gametophyte stage has become significantly reduced.123

The gametophyte, or prothallium, is typically a small, inconspicuous structure—often only 0.3 to 1 centimeter in size—that is usually one cell layer thick. Because it lacks the complex vascular system found in the sporophyte, it is limited in its ability to grow large or support complex tissues. In contrast, the sporophyte develops specialized tissues, including xylem and phloem, which allow it to transport water and nutrients efficiently, supporting the growth of roots, stems, and leaves.145

As the sporophyte matures, it becomes the independent, long-lived phase of the life cycle, while the parental gametophyte typically dies once the juvenile sporophyte becomes established.14