Galeopsis species - Hemp-nettles
There are three species of these arable weeds in Lanarkshire. They usually require to be in flower to tell them apart.
They are all roughly-bristly with spear-shaped, coarsely-toothed leaves.
The calyx has five widely spaced, spine-tipped spines.
Galeopsis tetrahit - Common Hemp-nettle
Corolla 12-20 mm long rarely more than 1.5 times the length of the calyx. Central lobe flat at most only slightly notched and the dark markings fall well short of the tip. Record Galeopsis tetrahit agg. if not in flower.
Galeopsis bifida - Bifid Hemp-nettle
Central lobe flat notched, folded downwards towards the margins. The dark markings extend almost to the edge.
Galeopsis speciosa - Large-flowered Hemp-nettle
Overall bigger, stem swollen below nodes with yellowish-tipped glandular hairs.
The lower lobe has a bold purple blotch and the upper corolla usually yellow. 27-35mm and twice the length of the calyx.