Betula nigra catkins long, the male catkins pendulous, the female catkins erect. The fruit is unusual among birches in maturing in late spring; it is composed of numerous tiny winged seeds packed between the catkin bracts. "Betula nigra" is a tree that falls into the family of Betulaceae, which is commonly known as the Birch or Alder Family. This family comprises six genera ("Alnus, Betula, Carpinus, Corylus, Ostrya," and "Ostryopsis)" and includes alders, birches, hornbeams, and hazelnuts. Species within this family, along with "Betula nigra", are shrubs or trees that grow along stream sides or in poorly drained soils throughout the Northern
Alnus viridis Alnus viridis Alnus viridis (green alder) is an alder distributed widely across the cooler parts of the Northern Hemisphere. It is a large shrub or small tree 3–12 m tall with smooth grey bark even in old age. The leaves are shiny green with light green undersurfaces, ovoid, 3–8 cm long and 2–6 cm broad. The flowers are catkins, appearing late in spring after the leaves emerge (unlike other alders which flower before leafing out); the male catkins are pendulous, 4–8 cm long, the female catkins 1 cm long and 0.7 cm broad when mature in late autumn, in clusters