=2.= =Populus heterophylla= Linnæus. Swamp Cottonwood. Swamp Poplar.
Plate 16. Tall trees up to 5-8 dm. in diameter; bark of old trees very
thick, broken into long ridges which are separated by deep furrows,
reddish-brown but generally weathered to ash-color; shoots densely
woolly at first, becoming glabrous before the second season; leaves
broadly-ovate with petioles 2-10 cm. long, more or less woolly on both
surfaces on unfolding, becoming glabrous above and remaining woolly
beneath, at least on the larger veins, rarely becoming entirely
glabrous, usually cordate at the base, blunt at apex, margins rather
regularly crenate-serrate; flowers in April; capsules ripening in June,
about 6 mm. in diameter, on stalks 5-10 mm. long; wood same as the next
species.
=Distribution.=--Along the Atlantic Coast from Connecticut to Florida
and along the Gulf to Louisiana, and northward along the Mississippi
Valley to Michigan. It is found in many parts of Indiana. In the
northern counties it is found in "gumbo" soils in swamps. It is a common
tree in the river swamps of the lower Wabash Valley where it reaches its
greatest size. There are no records for the extreme southeastern part
of the State, although it has been found in swamps in Harrison and Clark
Counties and is found in many counties of Ohio.
=Remarks.=--The pith of the shoots of this species is orange which
easily distinguishes it from all other species of the genus which have a
white pith. This species in all of its range is closely associated with
the common cottonwood, and millmen make no distinction in the price or
qualities of the timber.
=3.= =Populus deltoìdes= Marshall. Cottonwood. Carolina Poplar.
(_Populus balsamifera_ var. _virginiana_ (Castiglioni) Sargent). Plate
17. One of the largest trees of the Indiana forests; bark of very old
trees very thick, broken into ridges up to 1 dm. or more in thickness,
separated by deep furrows, reddish-brown, weathering to a gray; leaves
hairy on both surfaces as they unfold, soon glabrous except on the
margins which are more or less ciliate, broadly-deltoid, usually 7-12
cm. long, and about as wide, base more or less truncate or cordate, or
somewhat wedge-shaped, with rather short acuminate tips,
crenate-serrate; capsules ovate, about 6 mm. in diameter, on stalks 1-2
mm. long; wood light, soft, weak, sap wood white, heartwood small and
brown; warps badly on drying.
=Distribution.=--Quebec to Florida and west to the Rocky Mountains.
Throughout Indiana in low ground along streams, in swamps and about
lakes. On account of its habit of growing only in low ground it is
infrequent in the hill country of southern Indiana.
[Illustration: Plate 16.