Cooksonia

Cooksonia is a prehistoric genus of land plant. Cooksonia dates back to the Middle Silurian, all the way to the Early Devonian.^[1] Most fossils of Cooksonia were found in the United Kingdom in 1937.^[3] Cooksonia is known as the earliest plant with a xylem, and so it is considered to be a transitional fossil between Bryophytes (Mosses and others) and Vascular Plants. ^[4]

Cooksonia Temporal range: Wenlock to Early Devonian[1][2] PreꞒ Ꞓ O S D C P T J K Pg N
Reconstruction of Cooksonia
Scientific classification
Kingdom:	Plantae
Superdivision:	Polysporangiomorpha
Form taxon:	†Cooksonioidea
Genus:	†Cooksonia Lang, 1937
Type species
Cooksonia pertoni Lang, 1937

Only the sporophyte (or spore-bearing) phase of the plant is known, and was only a few centimeters tall. It does not have leaves or roots, though might be rooted through rhizomes.^[2]

References

1. Edwards, D. & Feehan, J. (1980), "Records of Cooksonia-type sporangia from late Wenlock strata in Ireland", Nature, 287 (5777): 41–42, Bibcode:1980Natur.287...41E, doi:10.1038/287041a0, S2CID 7958927
2. 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, S2CID 36688488
3. Lang, W.H. (1937), "On the plant-remains from the Downtonian of England and Wales", Philosophical Transactions of the Royal Society B, 227 (544): 245–291, Bibcode:1937RSPTB.227..245L, doi:10.1098/rstb.1937.0004
4. Freeman, Scott; Herron, Jon C. (2004). Evolutionary analysis (3rd ed.). Upper Saddle River, NJ: Pearson Education. p. 816. ISBN 978-0-13-101859-4.