These pictures of fossilized plants found in St. Clair, Pennsylvania. They grew in the Pennsylvanian or Late Carboniferous Period. Geologically they can be located in the Llewellyn Formation.
I think the plant in these pictures is called the
Sphenophyllum.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjBNgwowjnu8nyO5dfxjVWinK7U6ss8zXXGXDh5nWfLX1YQwYVGnc4eGBte2RG20GFWZg3S5QyV6_X5s83kqISirxyMallBwph_vXmVntGX9PWVGPqAcm4DGpbj-bMl_I49pt_B2ZNiF27Z/s400/sphenophyllum2.jpg)