Fig. 7.-Left: Orchid-tree;
 below: Foliage
 and flowers of the
 orchid tree Bau-
 hinia purpurea.


 Betula nigra. Betulaceae. River Birch. Northern area. Decid-
uous. Native.
 River birch grows to 50 feet and has a narrow, irregular crown
with alternate, simple, ovate leaves. Leaves change from a pale green
in spring to medium green in summer and to brilliant yellow in the
fall. Trees are distinguished by reddish bark peeling off in film-like
papery curls. Flowers are inconspicuous, borne in catkins, and 2 to 3
inches long. They appear before leaves in the springtime.