At one time, the entire club moss plant was used for medicinal purposes but now, because the plant contains harmful ingredients, only the spores are used.

    A few decades ago, it was still common for people to gather club moss plants, which resemble small evergreen trees, to make Christmas wreaths. I personally remember going into the forest in Massachusetts when I was a little boy to help my mother collect it. This should be discouraged because, while the plant is fairly common, it takes twenty years or more to mature. Some states have made collecting the wild moss illegal.

Note: a related herb named Chinese club moss has somewhat different uses.