I found this on my Ouse riverbank walk the other day. It's Great Horsetail or Equisetum telmateia.
It's in the same division as the ferns (Pteridophyta) as it reproduces by spores rather than seeds. It's one of two species in the genus that produce non-green cone-bearing shoots in Spring before the green, branched shoots that appear in Summer. It is one of the living fossils, being the only surviving genus from a class of plants that dominated the land back in the Carboniferous period when coal was being formed. Some species were trees reaching 30m in height.
|"Equisetopsida" by Rror Licensed under||CC BY-SA 3.0|