The term 'catkin-bearing tree' refers to four different species of trees: ALDER (5 letters), BIRCH (5 letters), HAZEL (5 letters), and Pussywillow (11 letters). These trees are characterized by their catkins, which are small, cylindrical flower clusters that appear in the spring. The catkins are usually yellow or green in color and are an important source of food for many animals. All four of these trees are native to Europe and North America and are often found in wetland areas.