Vascular Plants Include Seedless and Seed Plants

Vascular Plants Include Seedless and Seed Plants

Vascular plants arose during the Silurian period of the Paleozoic era. The extinct rhyniophytes may be ancestral vascular plants. These plants had photosynthetic stems (no leaves or roots) with sporangia
at theirtips. Most likely, the life cycle was similarto today's ferns. The sporophyte, which is diploid and has vascular tissue, is the dominant generation in ferns. The separate gametophyte produces flagellated
sperm. The sporophyte of seed plants produces heterospores which develop into heterogametes. Every aspect of the life cycle is adapted to a dry environment.