Cooksonia is a primitive land plant that lived during the Silurian and Devonian periods.
Only the sporophyte phase of Cooksonia is known, but at this stage the plant had a simple, branching stalk only a couple of centimeters in height. It had no roots, but it is possible that it grew from a rhizome instead. A spherical sporangium topped each branch. Some specimens of Cooksonia show that they possessed stomata and tracheids.
Cooksonia is believed to be a transitional form of plant between primitive bryophytes and the more advanced vascular plants.
There are six recognized species of Cooksonia, three of which are valid (the type C. pertoni, C. paranensis, and C. banksii) and three that remain doubtful (C. hemisphaerica, C. cambrensis, and C. bohemica).
- Boyce, C. Kevin (2008), "How green was Cooksonia? The importance of size in understanding the early evolution of physiology in the vascular plant lineage", Paleobiology 34 (2): 179–194, doi:10.1666/0094-8373(2008)034[0179:HGWCTI]2.0.CO;2
- Herron, Scott Freeman, Jon C. (2004). Evolutionary analysis (3rd ed. ed.). Upper Saddle River, NJ: Pearson Education. pp. 816. ISBN 978-0-13-101859-4.
- Gonez, P. & Gerrienne, P. (2010a), "A New Definition and a Lectotypification of the Genus Cooksonia Lang 1937", International Journal of Plant Sciences 171 (2): 199–215, doi:10.1086/648988