=5.= =Populus tremuloìdes= Michaux. Quaking Aspen. Plate 19. A straight
narrow tree up to 3 dm. in diameter, usually about 1-5 dm. in diameter;
bark usually smooth, greenish-white or gray, on older trees becoming
rough or fissured, and turning darker; shoots glabrous or with a few
hairs, turning reddish-brown the first season, later to a gray; leaves
of sprouts and very small trees usually ovate with a cordate base and
two or three times as large as leaves of older trees; mature leaves on
older trees variable, glabrous, the prevailing type has a bluish-green
leaf which is widely ovate or nearly orbicular, 3-7 cm. long, truncate
or slightly rounded at the base, usually abruptly short-pointed at apex,
finely and regularly serrate, the unusual type of leaf is thinner,
yellow-green, ovate, 2/3 as wide as long, rounded or wedge-shaped at
base, gradually tapering to a point at the apex, otherwise as the
prevailing form; stamens 6-12; capsules about 6 mm. long, on stalks
about 1 mm. long; wood light, soft and weak.
=Distribution.=--One of the most widely distributed of North American
trees. It ranges from Labrador south to Pennsylvania, thence southwest
to northern Mexico, and then north to northern Alaska. It is found at
sea level and at elevations of 10,000 feet. There are records of its
occurrence in all parts of Indiana. In all of its Indiana stations it
grows only in low ground about lakes, swamps, ponds, low places between
sand dunes, and along streams. In many places in the lake region it is
found in almost pure stands over small areas.
=Remarks.=--In Indiana this species is not of sufficient size and
abundance to be of much economic importance.
=JUGLANDÀCEAE.= The Walnut Family.
Trees with large, aromatic, odd pinnate leaves; flowers appearing after
the leaves unfold, the staminate in catkins, the pistillate solitary or
in clusters; fruit a nut in a fleshy or hard fibrous shell; kernel
edible or astringent.
Pith of twigs chambered; staminate catkins thick, sessile
or short stalked; stamens 8-40, glabrous; nuts with a
network of rough projections 1 Juglans.
Pith of twigs not chambered; staminate catkins slender,
long-stalked; stamens 3-10, hairy; nuts more or less
angled but smooth 2 Carya.
=1. JÙGLANS.= The Walnuts.
Trees with furrowed bark; pulp surrounding nut continuous, without lines
of dehiscence on the surface.
[Illustration: Plate 19.