Alder is a type of tree belonging to the genus Alnus, which is part of the birch family. These trees are commonly found in wetland areas and along riverbanks, thriving in moist soil. Alders are known for their distinctive catkins, which are cylindrical flower clusters that appear in early spring. The wood of alder is lightweight and often used in furniture making and woodworking. Alders play an important ecological role by fixing nitrogen in the soil, which helps improve soil fertility. This ability makes them beneficial for forest ecosystems and helps support the growth of other plants. Additionally, the trees provide habitat and food for various wildlife species, including birds and insects.