Water Horsetail - Equisteum fluviatile

There are two species of horsetail that are common around here.
The field horsetail (Equisetum arvense) grows on dry ground and is notable for its short, non-photosynthetic, unbranched reproductive shoots. (I may blip one another day).
The water horsetail (Equisetum fluviatile) grows in shallow water. Its reproductive bodies are at the top of tall photosynthetic stems that may be branched but here are generally unbranched. Stems are hollow.

Horsetails are primitive plants with relatives back in the Carboniferous period. They reproduce by spores produced in special bodies called strobili - two visible in my blip.