Temporal range: Wenlock–Early Devonian
|A drawing of Cooksonia.|
Cooksonia was first discovered in Britain, where most of the fossils come from. It thrived around the world. No fossil has been found of a Cooksonia producing gemetes, but rather spores.
Cooksonia is one of the oldest plants to have a stem with vascular tissue. It was also a non-vascular bryophyte.
Cooksonias were small (about 0.03-3mm), and lacked leaves. Each branch had a sporangium at their end for producing spores.
Some Cooksonia species had trancheids (Although not many).