Tempskya, growing millions of years ago

Tempskya is an extinct genus of tree-shaped ferns, the fossils of which have so far only been found in Cretaceous layers. The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic period 145 million years ago to the beginning of the Paleogene period 66 million years ago.

The stem-shaped structure of Tempskya is called "false stem" because it is formed by an entanglement of large numbers of stems and roots. The upward growing stems, which have a diameter of 2.5-10 mm, gave large numbers of roots (diameter about 1 mm) that grew downwards. They formed a felt-like mass around the stems. Because the stems branched regularly, a very solid whole was created. On a cross section of a trunk (see the images) the relatively large stems and the small roots can be seen.

 

From North America to anywhere else

Ceratophyllum demersum is a native of North America. It now has a worldwide distribution, at least in part due to the aquarium and pond trade. It is a submerged aquatic plant which is capable of forming dense monospecific beds, excluding other plant species, causing problems to recreational activities on waterways and in some cases causing blockages at hydroelectric power stations. C. demersum can spread rapidly, and grows in a large range of aquatic habitats.