Along the tow path just below Catfish Hole on the side away from the canal within view of the river. This has several fresh,fertile stems. I think I cut the head off of one in the photo. I needed to raise the angle a bit to get it in. This is the commonest of the Horsetails in MD and one of the few that has unbranched Fertile stems and branched Sterile stems, both of which can be seen here. It dies back in the fall and sends new stems up in the spring.
Equisetum arvense, the field horsetail or common horsetail, is a herbaceous perennial plant, native throughout the arctic and temperate regions of the northern hemisphere. It has separate sterile non-reproductive and fertile spore-bearing stems, growing from a perennial underground rhizomatous stem system. The fertile stems are produced in early spring and are non-photosynthetic, while the green sterile stems start to grow after the fertile stems have wilted, and persist through the summer until the first autumn frosts.