Life › Seas, forests & the move to land › Plants colonize land
Vascular plants (Cooksonia)
c. 430 million years ago· Evolutionary innovation· Plants & fungi
Well establishedStrong fossil, genetic or geological evidence.
Plants with internal water-carrying tubes that let them stand upright and grow taller; Cooksonia is the classic early example.
See it on the Life map →What happened
Vascular plants have xylem, tubes of reinforced cells that carry water up from the ground, and phloem, which moves sugars. Cooksonia, from about 430 million years ago, was only a few centimeters tall: leafless, rootless forked stems tipped with spore capsules. Over the next 40 million years vascular plants evolved roots, leaves and wood. Today they include ferns, conifers and flowering plants, over 90% of land plant species.
Why it matters
Internal plumbing freed plants from hugging damp ground, allowing height, competition for light, and eventually trees, forests and most food on land.
Think of it like
Like a building's riser pipes: without them, nothing much grows above the ground floor.
The evidence (fossils, genes, rocks)
Fossil stems from Silurian rocks in Ireland, Wales and the Czech Republic, some with preserved water-conducting cells; Cooksonia was named by William Lang in 1937.
Still debated
Whether all Cooksonia-like plants had true xylem, and whether Cooksonia was one plant group or several look-alikes.
Connections (2)
▸Plants colonize land led to Vascular plants (Cooksonia)Well established
The connection
The first land plants were short because they had no plumbing to move water. Some evolved xylem, tubes of reinforced cells that carry water up from the ground and stiffen the stem. That let plants such as Cooksonia stand taller, a few centimeters at first, and branch, setting up later trees.
When and how
Silurian period, about 430 million years ago; Cooksonia fossils come from Ireland, Wales, the Czech Republic and elsewhere.
The evidence
Fossil stems with preserved water-conducting cells, and the shared anatomy and DNA of living vascular plants.
Debates and open questions
Whether all Cooksonia had true xylem is uncertain, and how mosses and liverworts relate to vascular plants is still debated.
▸Vascular plants (Cooksonia) led to First trees & forestsWell established
The connection
Water-conducting tissue made height possible. Over roughly 40 million years, vascular plants added wood stiffened with lignin, leaves and deeper roots, growing from ankle-high stems to trees several meters tall. By about 390–385 million years ago they formed the first forests.
When and how
Devonian period worldwide; the earliest forests are in Somerset, England (about 390 million years ago) and Gilboa and Cairo, New York (about 386–385 million years ago).
The evidence
A clear sequence of fossils from small Silurian stems to Devonian trees in dated rock layers, including fossil stumps still standing where they grew.
Debates and open questions
Wood and tree size evolved more than once, and how different early tree groups gained height independently is still being worked out.