Types

• Vascular plants form what evolutionary biologists call a clade, meaning a group consisting of a common ancestor and all its descendants. The common ancestors of this group lived about 420 million years ago. The key characteristic that defines all members of this group is the presence of specialized vascular tissue, which conducts water, minerals and nutrients throughout the plant.
  
  

Function

• Since they could transport water from one part of the plant to another, vascular plants could grow much taller than nonvascular plants like mosses. Among the important adaptations they developed are roots and leaves; the former anchored the plants and helped them to extract nutrients, while the latter provided increased surface area for photosynthesis.
  
  

History

• During the late Devonian and early Carboniferous Periods some 400 million years ago, vast swamp forests of giant seedless vascular plants -- relatives of today's ferns and horsetails -- grew across many regions of North America and Europe. As plants used up carbon dioxide, atmospheric CO2 concentrations decreased nearly fivefold, leading to climate change, glacier formation and the end of the swamp forests. As the large seedless vascular plants died off, seed plants took their place.