This is common toadflax (Linaria vulgaris) growing by the side of a busy road. It's by no means a rare plant and is a favourite of bees who need to be fairly strong to get at the nectar hidden in the snapdragon like flower. The plant has many names relating to the colour , butter and eggs as I've indicated but also bread and butter, butter haycocks and yellow rod. Other names seem to be local folk making stuff up to please themselves so here's a small sample of alternative names: brideweed , rabbit flower, bunny mouth (?) and calf's snout (??). My favourite though, among the many names, has to be dead men's bones which might possibly relate to the practice of using the plant medicinally, who knows?
