We live in Southern Ontario Canada, and I was wondering where the spores from horsetail come from? My neighbour is claiming that the horsetail in her garden came from our pea gravel that we have in an area of our yard. (We have no horsetail in our gardens). I've read as much as I could on this plant and I've found nothing that indicates that the spores come from pea gravel and I would like clarification on this if anyone knows. Much thanks in advance!

I don't know why she would assume that. The spores could be travelling from anywhere in the neighbourhood, not especially from your pea gravel. That is so funny ! If she doesn't like them, tell her to pull them up.

Airborne spores from those growing in a nearby pond or lake. Must be a very wet area.