Willows in Flower

Nothing announces the coming of spring quite like the willows (Salix). Comprising some 350 species of trees and shrubs, the willows are among the earliest woody plants to leaf out in spring and among the last to drop their leaves at season's end. As early as January and February, many willows sport yellow to light-green new growth that stands out in the stark winter landscape, and shrub species commonly known as pussy willows exhibit the hairy flower scales that inspire their common name. Throughout North America, our common pussy willow (S. discolor) attracts early emerging pollinators and hosts several butterfly and moth species during the growing season. The rosegold pussy willow (S. gracilistyla) is a beautiful shrub from Japan, Korea, and China that is prized in horticulture as one the earliest flowering pussy willows.

At the tail end of winter, flowers begin as fuzzy nubs along the branches of pussy willows. The soft coating of hairs acts as insulation to protect these early bloomers from cold temperatures. Individual plants bear either male (pollen-producing) or female (seed-producing) flowers which have no sepals or petals and are borne in large numbers on catkins. When blooming, male catkins feature beautiful yellow to orange to red anthers (pollen sacs) that then split open to display bright yellow pollen inside. After the pollen has been dispersed by wind or visiting insects, the anthers appear black. Female catkins are typically smaller and less showy and tend to emerge later than the catkins borne on male plants. Willows grow best in moist environments, so many of the Arnold Arboretum's pussy willows grow in and around the wet meadow inside the Arborway Gate.

Learn more about willows and Boston's museum of trees at arboretum.harvard.edu. Open every day. Free every day.