British dock, more...
[Rumex acutus auct., non L. (pro sp.), more]
Etymology: Rumex: the ancient Latin name for the docks or sorrels
Plants: erect, perennial, up to 8' tall, stout forb; stems unbranched to the inflorescence
Leaves: mostly flat, lance-like, large, 6" long
Flowers: yellow, 6-parted, stalk with a vague joint near the base when mature; inflorescence up to 20" long, branched cluster often with small leaves at the base of the branches
Habitat: swamps, shallows