Galeopsis speciosa Large-flowered Hemp-nettle C DD N
This plant puzzled me when I first discovered it in a field a few hundred metres from home. One year there would be dozens of plants the next none at all. Then it dawned on me that this was a typical arable weed which needs to be in the soil for a while and then exposed to the elements (probably light) by ploughing. Sure enough whenever the soil is ploughed or moved in any way it appears in August. If it the field is left fallow then at most one plant will appear. As the name suggests it is a member of the nettle family but the beautifully marked flowers make it one of the treats of high summer botanising.
G. speciosa prefers the north to the south and although dotted here and there in southern central England, there isn't so much to be found there. In North Wales, Lancashire, Yorkshire, southern Scotland and around the Aberdeen hinterland, there is plenty to be found. In Ireland too it prefers the north and there are few records from the central and southern regions.