The willows along Putah Creek are looking fuzzier than usual this time of year. Upon closer inspection, they are actually adorned in green or yellow inflorescences (flower clusters) shaped like caterpillars, and might even be giving off cottony tufts of seeds.
One especially shapely willow tree common to Putah Creek is red willow (Salix laevigata). Red willow is a medium sized deciduous tree, growing up to 40 feet tall from winding trunks. Its red to brownish twigs are flexible and easily snap off at the base, and its glossy green leaves are narrow, spear shaped, and pointy at the tip, and are dull gray-green underneath.
Like all willows, red willow is dioecious, which means it has separate flowers for its male and female parts, and these flowers are housed on different trees. Both types of flowers appear as unshowy, drooping catkins, designed for wind pollination, but the cottony seeds are produced only by the female flowers.
The ability of willows to grow readily and quickly in heavy, wet soils, make them useful in restoration for helping minimize soil erosion near waterways. Like other willows, red willow is well adapted to flooding. Branches broken off during disturbance sprout easily to create new plants where they lodge in banks downstream. Restoration practitioners take advantage of this characteristic to encourage establishment of new plants by driving cuttings directly into the soil near water.
Red willow provides wildlife cover and nesting habitat in the mid-story layer of the riparian forest. In the spring, insects swarm and feed on willow nectar and birds feed on the seed. It and other native willows serve as host plants for several butterflies, including Lorquin’s Admiral (Limenitis lorquini), Willow Hairstreak (Satyrium sylvinus), and Mourning Cloak (Nymphalis antiopa).
Willows are an essential basket weaving material for indigenous people of California. Suitable basket materials are produced through burning or regular pruning of the trees. Traditional house frames, fences, sweat lodges, arrow shafts, and medicines are also created using willow. The pain reliever aspirin is a synthetic derivative of salicylic acid, a bitter medicinal compound found in willow bark, and the namesake for the family of plants that willows belong to, Salicaceae.