Leaves chalky-white tomentose beneath, some of them more or less lobed, blades 6-10 cm. long 1 P. alba.

Leaves p.u.b.escent or whitish tomentose while young, never lobed, blades 10-17 cm. long 2 P. heterophylla.

Petioles strongly flattened laterally especially near the blade.

Winter buds more than 8 mm. in length, stamens more than 20, capsules more than 3 mm. in diameter, leaves broadly deltoid, majority more than 8 cm. wide 3 P. deltoides.

Winter buds less than 8 mm. in length, stamens fewer than 20, capsules less than 3 mm. in diameter, leaves roundish ovate, majority less than 8 cm. wide.

Winter buds more or less p.u.b.escent, dull; leaves generally with less than 12 teeth to a side 4 P. grandidentata.

Winter buds smooth or rarely somewhat p.u.b.escent, glossy; leaves with more than 12 teeth to a side 5 P. tremuloides.

=1.= =Populus alba= Linnaeus. Silver-leaf Poplar. Plate 15. Short-trunked trees with a round top, up to a meter or more in diameter; bark on young trees smooth, greenish-white or gray, becoming furrowed on old trees, gray or dark brown; shoots white tomentose, becoming smooth in age; leaves ovate or triangular, 3-5 lobed or irregularly toothed, hairy on both surfaces on expanding, becoming dark green and glabrous above, remaining white tomentose beneath; stamens about 8; wood light, soft and weak.

=Distribution.=--Introduced from Europe and escaped in all parts of the State.

=Remarks.=--This tree has long been under cultivation, and several horticultural forms have been introduced. It is falling into disuse on account of its habit of sending up root shoots. It adapts itself to all kinds of soil, grows rapidly, transplants easily, stands pruning well and has few insect or fungous enemies.

[Ill.u.s.tration: Plate 15.

POPULUS ALBA Linnaeus. Silver-leaf Poplar. ( 1/2.)]

=2.= =Populus heterophylla= Linnaeus. 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 a.s.sociated with the common cottonwood, and millmen make no distinction in the price or qualities of the timber.

=3.= =Populus deltodes= 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 ac.u.minate 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.

[Ill.u.s.tration: Plate 16.

POPULUS HETEROPHYLLA Linnaeus. Swamp Cottonwood. ( 1/2.)]

[Ill.u.s.tration: 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.

=4.= =Populus grandidentata= Michaux. Large-toothed Aspen. Plate 18. A small or medium-sized tree, 1-4 dm. in diameter; bark smooth, grayish-green or whitish, becoming furrowed and dark brown on the trunks of old trees that grow in the northern part of the State, especially when growing in a swampy habitat. In the southern part of the State where the tree usually grows on the top of hills, the bark does not darken so much, frequently remaining a light to dark gray until maturity. Shoots more or less woolly at first, becoming glabrous, reddish-brown; leaves on sprouts and very young trees very velvety beneath, slightly hairy above, ovate in outline, cordate at base and with blades up to 20 cm. in length; leaves on older trees a yellow green, glabrous, ovate, blades usually 6-10 cm. long, coa.r.s.ely and unevenly toothed, the base slightly rounded, rarely truncate or slightly cordate, the apex pointed or rounded; petioles strongly flattened laterally; stamens 6-12; capsule about 5 mm. long on a stalk about 1 mm.

long; wood soft, light and not strong.

=Distribution.=--Nova Scotia west to northern Minnesota and south to the Ohio River, and along the Alleghany Mountains to South Carolina. Found throughout Indiana, except we have no authentic records for Gibson[11]

and Posey[12] Counties. In the northern part of Indiana it is found in great colonies about lakes, etc. or rarely a few trees on the crests of gravel and sand ridges. In southern Indiana it is found in the "k.n.o.b"

area in small colonies on the tops of the ridges a.s.sociated with scrub pine and chestnut oak and is rarely found in low ground in this part of the State.

=Remarks.=--This species is too rare to be of much economic importance.

It could be most profitably used for excelsior and pulp wood.

[Ill.u.s.tration: Plate 18.

POPULUS GRANDIDENTATA Michaux. Large-toothed Aspen. ( 1/2.)]

=5.= =Populus tremulodes= 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.

=JUGLANDaCEAE.= 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 cl.u.s.ters; fruit a nut in a fleshy or hard fibrous sh.e.l.l; 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. JuGLANS.= The Walnuts.

Trees with furrowed bark; pulp surrounding nut continuous, without lines of dehiscence on the surface.

[Ill.u.s.tration: Plate 19.

POPULUS TREMULOIDES Michaux. Quaking Aspen. ( 1/2.)]

Bark gray, ridges smooth; upper part of leaf-scar of last year's twigs with a mat of hairs; pith dark-brown; fruit oblong, husk clammy 1 J. cinerea.

Bark dark brown, ridges rough; upper part of leaf-scar of last year's twigs without a mat of hairs; pith light brown; fruit orbicular to slightly elongate, husk not clammy 2 J. nigra.

=1.= =Juglans cinerea= Linnaeus. b.u.t.ternut. Plate 20. A medium sized tree, usually less than 6 dm. in diameter; leaf-scars with upper margin convex or rarely notched; leaves 3-6 dm. in length; leaflets 7-19, the middle pairs the longest, clammy, almost sessile, oblong-lanceolate, 6-12 cm. long, fine serrate, rounded at base and ac.u.minate at apex; flowers in May or June; fruit ripens in October, 4-8 cm. long with 4 prominent longitudinal ridges; kernel sweet and very oily; wood light, soft, not strong, coa.r.s.e-grained but takes a good polish.

=Distribution.=--Valley of the St. Lawrence River south to the Gulf States and west to Nebraska. Found in all parts of Indiana, although very sparingly in some counties. It is an infrequent tree in our range, and in only a few localities is it frequent or common. It is found along streams and in ravines, and in two instances it has been noted in old tamarack marshes. It prefers a well drained gravelly soil, and is rarely if ever found in a compact soil.