Common Hemp-nettle

Galeopsis flowers always look to me like a person with a chinese hat :-)
The flowers are multicolored, with purple, pink, or white areas
It is a herbaceous annual plant growing to 1 m tall. The stems have reflexed hairs and swollen nodes. In cross section, the stem is square. The leaves are rhombic to elliptic, with coarsely to bluntly serrate edges.