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Botany Photo of the Day
In science, beauty. In beauty, science. Daily.

Cooksonia

Cooksonia pertoni
Cooksonia sp.

From a prehistoric plant series that Alexis assembled over the summer:

Today's first photo shows a fossilized specimen (about 2.5cm tall) of Cooksonia pertoni from Shropshire, England, dating from the Upper Silurian. Much thanks to Hans Steur for permitting us to share his work!

The second photo shows a model of Cooksonia found in the Evolution House at the Royal Botanic Gardens, Kew. Thanks to Drew (Drew Avery@Flickr) for sharing the photo! Along with fossils, these models can help us imagine what Earth's early plant life may have looked like.

In 1937, British botanist William Henry Lang was the first to describe the extinct genus Cooksonia, based on specimens he found in Wales. From his findings, he identified two species: Cooksonia pertoni and Cooksonia hemisphaerica. Since then, more fossils of the genus dating from the Silurian to Lower Devonian have been found in Europe, Africa, and North America (see: Thomas and Spicer's The Evolution of Palaeobiology of Land Plants (1987)). It should also be noted that Cooksonia is not considered to be an evolutionary clade (not all the species have a common ancestor), but rather it is a grade, a group in which species share similar morphology.

Cooksonia is often credited with being the "first vascular land plant." Despite its reputation, however, it is uncertain whether all Cooksonia species were vascular. Some fossilized impressions show evidence of vascular tissue in the form of a dark strand in the centre of the plant's axis, but not all Cooksonia specimens do. What is certain is that Cooksonia was a small plant, no larger than 15cm tall, possessing several distinctive features such as a dichotomous branching pattern, lack of true leaves, and sporangia found on the tips of the branches, that are now associated with other early land plants.

9 Comments

Diana Ferguson commented:

What a terrific series. Thanks for this idea and these pix.

Maggie commented:

Wow! It's pretty amazing how life managed to figure out a way to reproduce itself. When I look at the sporangia evident in the fossil, I wonder how such a small, delicate organism came to be "enshrined" in rock. As a botanist/biologist, I know (as much as anyone knows anything) the mechanism(s) that occurred, but it still never ceases to amaze me! Thanks for the photos and the writeup.

Connie commented:

Thank you for drawing our attention to so many incredible amazing plants. This fossil correlation is so interesting.

Ruth Stockey commented:

Hurray for a fossil plant making the plant of the day! But what I want to know is where the leaf litter and soil (around the reconstruction) came from?

kcflowers commented:

I also want to say that this is a fantastic series; so interesting, educational, and different.

elizabeth a airhart commented:

amazeing in our expanding universe what will the future find

thank you daniel and company

Rob Clack commented:

Jenny and I found, and inexplicably, threw away (yes, I know!) a specimen of Cooksonia loose on the shore at West Angle Bay, Pembrokeshire, Wales, in the mid-1990's. Returning to the site, we were unable (surprise!) to find any more. We suppress our embarrassment to ensure the world knows about the locality.

moreza commented:

hi there , i have a tiny plant fossil in a rock that i think should be some type of cooksonia perhaps pertoni .could i possibly send you a picture of it please for accurate identification ?
thanks in advance . yours Moreza

Daniel Mosquin commented:

Moreza, I would track down someone who works directly with Cooksonia fossils (see some of the names above). No one at the garden currently has expertise in this area.

Comments are closed.

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