Archaeopteris is an extinct genus of progymnosperm tree with fern-like leaves. A useful index fossil, this tree is found in strata dating from the Upper Devonian to Lower Carboniferous, the oldest fossils being 385 million years old, and had global distribution.
A reconstruction of Archaeopteris macilenta from the Late Devonian, Walton Formation of Hancock, New York
A polished round of permineralised wood of Callixylon whiteanum from the Late Devonian Woodford Shale of Ada, Oklahoma
Plants are the eukaryotes that form the kingdom Plantae; they are predominantly photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with cyanobacteria to produce sugars from carbon dioxide and water, using the green pigment chlorophyll. Exceptions are parasitic plants that have lost the genes for chlorophyll and photosynthesis, and obtain their energy from other plants or fungi.
Image: Frühling blühender Kirschenbaum
Image: Micrasterias radiata
Image: Glaucocystis nostochinearum