The most common horsetail found in the area, and at the FWG. This is the fertile stem which will soon disappear, and in its place you will see the green sterile stems. Horsetails (also called scouring rushes)are an ancient plant group, and according to the Peterson field guide to the ferns, "they are considered one of the oldest of the Pteridophytes (fern families), being closely allied to the prehistoric Calamitales,large and abundant treelike plants that flourished 300 million years ago." So think of that next time you look at these plants! It is not hard to imagine them in a prehistoric setting, particularly when you look at huge swathes of the bigger ones such as Equisetum hyemale.