Cordaites is a genus of extinct gymnosperms, related to or actually representing the earliest conifers. These trees grew up to 100 ft tall and stood in dry areas as well as wetlands. Brackish water mussels and crustacea are found frequently between the roots of these trees. Cordaites fossils are most commonly found in rock sections from the Upper Carboniferous of Europe and the Americas. A number of many types from this line are: In contrast to many other plants, fossilized Cordaites seeds are not rare, because they are rather large (up to 10 mm); those seeds are named Cordaicarpus.