Betula papyrifera very toxic to paper birch. It is frequently planted as an ornamental due to its graceful form and attractive bark. The bark changes to the white color at about 3 years of growth. Paper birch grows best in USDA zones 2-6, due to its intolerance of high temperatures. "Betula nigra", or river birch, is recommended for warm-climate areas warmer than zone 6 where paper birch is rarely successful. "B. papyrifera" is more resistant to the bronze birch borer than "Betula pendula" which is similarly planted as a landscape tree. Birch skeletonizer is a small larva which feeds on the leaves
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