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 cordata with a very long season in leaf, from April to December in the Northern Hemisphere; they are alternate, cordate (heart-shaped), rich glossy green, 5–12 cm long, with a finely serrated margin. The slender cylindrical male catkins are pendulous, reddish and up to 10 cm long; pollination is in early spring, before the leaves emerge. The female catkins are ovoid, when mature in autumn 2–3 cm long and 1.5–2 cm broad, dark green to brown, hard, woody, and superficially similar to some conifer cones. The small winged seeds disperse through the winter, leaving the old woody, blackish 'cones' on the tree