Have you ever seen something like this? It’s a goldenrod plant in the late spring, before flowering. The top of the plant is growing a flower-like cluster of leaves.
This is called a goldenrod rosette gall. An insect called a goldenrod gall midge (Rhopalomyia solidaginis) has laid its eggs on the top of the goldenrod stem, and that has stimulated the plant to grow abnormally. The stem stops growing, but the leaves continue to grow, forming a rosette.
The next time you are out on the trail, look for the goldenrod plants, and let me know if you see a gall like this!