=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. POPULUS HETEROPHYLLA Linnæus. Swamp Cottonwood. (× 1/2.)] [Illustration: Plate 17. POPULUS DELTOIDES Marshall. Cottonwood. (× 1/2.)] =Remarks.=--The cottonwood is adapted to a moist soil, propagates easily, grows rapidly and is one of the best trees for forestry purposes for planting overflow lands, and for planting where a quick shade is desired or for temporary windbreaks. The leaves of this tree are quite variable and several forms have been described. The Carolina poplar of nurserymen has an upright habit of growth and was formerly much planted as a shade tree. Its undesirable qualities have condemned it, and most cities now prohibit its planting. Cottonwood has many uses, and was formerly a very important timber tree, but the supply has so diminished that large trees have become quite scarce. The thick bark was much used by the boys of the pioneers for whittling out toys, etc.