Which horsetail?

Which horsetail?

Observation - Which horsetail?. Description: Horsetails around 2 foot high growing in marshy ground around fringe of a pond in Wiltshire. E. arvense I think, but am not sure how to separate this species from other possibles for sure.

Horsetails around 2 foot high growing in marshy ground around fringe of a pond in Wiltshire. E. arvense I think, but am not sure how to separate this species from other possibles for sure.