Argentinian Vervain

Argentinian Vervain

Observation - Argentinian Vervain. Description: I spotted a number of these plants while walking along the river in Worcester centre. The bank is rich with wild flower species but I can't say if they are natural or planted. It stood as tall as the Black Knapweed growing close by. The long hairy stalk

I spotted a number of these plants while walking along the river in Worcester centre. The bank is rich with wild flower species but I can't say if they are natural or planted.
It stood as tall as the Black Knapweed growing close by. The long hairy stalk has small leaves growing in opposite pairs.