On one level the possession of vascular tissue—xylem and phloem—separates the ferns and their allies from the bryophytes and the lack of seeds from the gymnosperms and angiosperms. Other character-istics they share in common are more varied and include: • An alternation of a haploid gametophyte phase with a diploid sporophyte, a sporic meiosis. The gametophyte and sporophyte are nutritionally independent of one another. • The sporophyte is the dominant, often branched, long-lived phase (the leafy fern plant is the sporophyte, for example). Many are perennial and vegetative (asexual) reproduction is common. • The gametophyte is smaller and either photosynthetic or saprophytic. Because the flagellated sperm need water in which to swim to the egg (like bryophyte sperm), the gametophyte is restricted in distribution by habitat. The plants are oogamous.
This is the end of the preview. Sign up
access the rest of the document.