Birch . — The papery bark with horizontal “breathing pores” 
( lenticels ) and the slender terminal twigs characterize the birches. 
The leaves are simple pinnate, with serrate margin. The birches 
are also monoecious; both kinds of flowers are in catkins. They 
open in early spring, and the pistillate catkins remain on the tree 
till winter. The fruits are small, one-seeded nuts, usually 
winged. The white birch is often seen on lawns; the smaller 
gray birch is common in woods. The leaves of the gray birch 
are more pointed than those of the white birch; there are dark 
marks more or less triangular under the branches, and the 
smaller branches are usually brown (not white, as in the white 
birch). The sweet black birch is known by its dark bark, and its 
twigs have a very distinct, pleasant taste. 
Linden .— Linden trees are common on the streets. The leaves 
are alternate and heart-shaped, with serrate margin. The Amer- 
ican linden, also called basswood, has a smoother bark and 
coarser leaves than the European species. The small, cream- 
colored, fragrant flowers hang from an expanded leafy bract, and 
.develop into woody, globular fruits. 
Tulip Tree . — Thetuliptree is one of the largest and most use- 
ful of American trees. It is a rapidly growing tree. Its smooth 
three-lobed leaves, with the end apparently cut off ( truncate ) are 
very distinctive. The stipules, which serve as bud-scales, fall off 
early in the season, leaving a ridge around the twig. The tulip- 
shaped, greenish yellow flowers grow mostly on the upper 
branches. The fruit is cone-like, a part of it often remaining on 
the tree through the winter. 
Some other genera of deciduous trees seen in Brooklyn are 
walnut, hickory, alder, hornbeam or blue beach, hop-hornbeam 
or ironwood, beech, hackberry, mulberry, magnolia, sassafras, 
sweet gum, hawthorn, mountain ash, cherry, locust, honey locust, 
Judas tree, dogwood, tupelo, ash, and catalpa; these are native 
of this region. Introduced trees are apple, pear, plum, peach, 
cherry, ginkgo, cercidiphyllum, Kentucky coffee tree, yellow- 
wood, ailanthus or tree of heaven, varnish tree, and paulownia. 
A. Gt'NDEUSEN. 
