WWCA Site 6 on S Fk Wolf Creek. Equisetum laevigatum or E. hyemale? Commonly known as horsetail fern.

I notice that the joints are telescopic. Black or black, gray, black joints and fluorescent green above the joints, more double banded at the bottom and single at the top, with a button where the fruit or flower was at the top. Some joints have smaller, jointed branches growing to the side. They grow close together about 5 or 6 feet high, just above the stream banks, extending on the flat for about 3 meters.

I wonder
What the root system is like?
What uses there are for it?
Are they typically found by streams?

My guess is that they have a common root system for many plants.