Family: Lamiaceae (Mint family).
Native of Europe and western Asia.
Occurrence: A weed of damp places e.g. streamsides and roadside ditches. In Europe it is sometimes called "Lurk in the Ditch".
It is sometimes used as a medicinal or culinary herb. Some parts are poisonous.
Photos 1, 2, 4: Pennyroyal. Meins Lane, Guildford Plateau, growing in a roadside depression.
3, 5: Forest Creek.