The willows are a large family, ranging from tall, stately trees, providing a useful source of timber, to ground-hugging shrubs found in some of the coldest regions of the north. Woolly willow is one of the latter types, and although it can reach a height of well over a metre, the plant’s characteristics reflect the harshness of its environment. Willows, in fact, have adapted themselves more than any other tree type – even the pines – to the cold northern latitudes.
Like all willows, this species is ‘dioecious’, occurring as either male or female trees. Woolly willows’ catkins appear during the month of June in Scotland. Female catkins are insect-pollinated, unlike nearly all other native catkin-bearing trees, such as the hazel, beech and oak and even the related poplars, which are wind-pollinated. They provide an important source of food for insects, especially bumblebees, at that time of year.