Locust wood is somewhat lighter than white oak, but it is 34 percent stiffer and 45 per cent stronger. These remarkable qualities added to its durability in contact with the ground make it one of the most desirable trees for forest planting. The wood has been used princ.i.p.ally for posts, ties, tree nails, etc. The locust when grown close together usually grows to 8-12 inches in diameter. There are, however, specimens that have grown in the open that are almost three feet in diameter. The pioneers used it extensively for ornamental planting, and it has escaped from such planting in all parts of the State. It propagates easily by root shoots which is the princ.i.p.al mode of spreading, except where the seed fall on exposed soil.

[Ill.u.s.tration: Plate 109.

ROBINIA PSEUDO-ACACIA Linnaeus. Black Locust. ( 1/2.)]

The locust has of recent years been extensively planted for post timber.

It is very easily propagated from seedlings and grows rapidly. It is adapted to all kinds of soil, except a wet one. It prefers a well drained soil and seems to grow as fast in a loose clay soil as in a black loam. When used for forest planting the s.p.a.cing should be from 5 5 feet to 8 8 feet. The s.p.a.cing should be governed by the quality of the soil, and the amount of pruning that can be done. The locust has the habit of having the terminal to end in a fork and having one or more very large side branches. The best management requires that the very large side branches be removed as soon as they are noted, and one part of the terminal forks be cut off.

The locust until recently gave great promise of being an important tree for planting sterile, washed and eroded slopes, on which it usually thrives and in many cases grows thriftily. However, reports from all parts of the State show that locust groves wherever planted are being killed by the locust body borer. The locust has also been attacked by the twig borer, bag worm and the leaf miner. At present there are no known economic means of controlling these destructive pests, and until they can be controlled, the planting of locust for commercial purposes will not prove profitable.

=SIMARUBaCEAE.= The Qua.s.sia Family.

=AILaNTHUS.= Tree of Heaven.

=Ailanthus altissima= (Miller) Swingle. Tree of Heaven. Stink Tree.

(_Ailanthus glandulosa_ Desfontaines). Plate 110. Medium sized trees with dark gray bark, thin, rough or fissured on old trees; branchlets very robust; twigs smooth; leaves compound and very large, especially on coppice shoots, usually about 4-6 dm. long, odd-pinnate, arranged spirally on the branchlets; leaflets 13-41, ovate-oblong, ac.u.minate, oblique at base, entire or with a few blunt teeth toward the base, smooth or hairy when they unfold, becoming smooth at maturity, dark green above, lighter beneath; flowers appear in June in large terminal panicles, the staminate and pistillate on different trees; fruit maturing in autumn, consists of many light brown, twisted and broadly-winged samaras which are about 1 cm. wide and 4-5 cm. long.

=Distribution.=--A native of China. Introduced and spreading in cities, and into fields and woods in the southern part of the State. The most notable occurrence is in Jefferson County on the wooded bluffs of the Ohio River between Madison and Hanover.

=Remarks.=--Where the sugar and black maple can not be used for shade tree planting this tree should receive attention. It adapts itself to all kinds of soils, and to all kinds of growing conditions such as smoke, etc. The crown is of an oval or rounded type. It stands pruning and injury to trunk or branches quite well. It is practically free from all diseases and insect injury. The leaves appear late but they do not fall until the first killing frost when they are killed, and frequently practically all of the leaves will fall in one day. The staminate flowers exhale a fetid odor for a few days which is about the only objectionable feature in this tree. In order to obviate this objection, nurserymen are now offering for sale pistillate trees which have been grafted on common stock.

[Ill.u.s.tration: Plate 110.

AILANTHUS ALTISSIMA (Miller) Swingle. Ailanthus or Tree of Heaven.

( 1/2.)]

=ACERaCEAE.= The Maple Family.

=aCER.= The Maples.

Trees with terete branches; scaly buds; long petioled, opposite leaves; fruit consists of two long-winged samaras which are joined at their base, separating at maturity. The sap of some of the species, when concentrated, yields the maple sugar and sirup of commerce.

Leaves trifoliate or pinnate 1 A. Negundo.

Leaves simple.

Winter buds blunt; flowers appear from lateral buds before the leaves; fruit maturing in the spring or early summer.

Leaves entirely glabrous beneath at maturity, 5-lobed; the two sinuses between the three largest lobes generally somewhat closed, formed as it were by the arcs of two circles which meet to form the sinus, and which if they were extended outward would cross each other within a few dm. of the sinus; fruit more or less p.u.b.escent at maturity 2 A. saccharinum.

Leaves are never all entirely glabrous at maturity, 3-5 lobed; the two largest sinuses are generally angular with straight sides which if extended outward would never cross; fruit smooth at maturity.

Twigs smooth at maturity; leaves at maturity smooth beneath except a few hairs in the axils of the veins, or more rarely the entire lower surface covered more or less with a short p.u.b.escence; mature fruit generally 2-3.5 cm. long 3 A. rubrum.

Twigs more or less p.u.b.escent at maturity; leaves beneath covered with a dense tomentum which remains until maturity or sometimes becoming scanty; fruit about 4-5 cm. long var. Drummondii.

Winter buds acute, sometimes somewhat blunt; flowers appear from terminal buds after the leaves; fruit maturing in the autumn.

Leaves yellow green beneath; base of the petiole of the terminal leaves enlarged at the base, smooth or somewhat p.u.b.escent about the enlarged base. 4 A. nigrum.

Leaves not yellow green beneath; base of the petiole of the terminal leaves not enlarged, petioles smooth, or if p.u.b.escent at the base the p.u.b.escence will be more or less evident the entire length of the petiole.

Petioles smooth; leaves 3-5 lobed, blade as long or longer than wide, not densely p.u.b.escent beneath at maturity. 5 A. saccharum.

Petioles smooth; leaves 3-lobed, blades wider than long. A. saccharum var.

Rugelii.

Petioles p.u.b.escent, rarely smooth; leaves 5-lobed, rarely 3-lobed, the under surface densely p.u.b.escent at maturity. A. saccharum var.

Schneckii.

=1. Acer Negundo= Linnaeus. Box Elder. Plate 111. A medium-sized tree with a short trunk and round head; bark of young trees smooth and gray, becoming thick on old trees, light to dark brown and more or less furrowed or rarely somewhat flaky; twigs smooth and greenish; leaves of average size are 1.5-3 dm. long, generally with 3 leaflets on the flowering branches, sometimes 5 or rarely with 7, on sterile branches or on growing shoots 3-7, the petioles generally 1/3-1/2 the length of the leaf and glabrous or nearly so at maturity; leaflets all on stalks more or less p.u.b.escent, the lateral stalks short, the terminal ones much longer, leaflets of varying size and shape, the margins usually varying from lobed to serrate or entire, pinnately veined, smooth above at maturity and remaining more or less p.u.b.escent beneath, especially along the veins; flowers appear just before the leaves the last of April or the first of May, the staminate and pistillate on separate trees; fruit matures late in summer, the body of the samara green and more or less p.u.b.escent.

=Distribution.=--New England to Florida, west to Minnesota and south to eastern Texas. In Indiana, it is found throughout the State in moist or wet places along creeks and rivers, and infrequently on the highlands along roadsides and fences. Its original distribution in the State can only be conjectured. Judging from its tolerance to shade and its habitat, and from the earliest reports of its occurrence in the State, this species was quite rare in the northern part of the State, becoming infrequent to frequent in its habitat in the southern part of the State.

Even today it is rather local in its distribution. I have never seen it on the low mucky border of a lake.

=Remarks.=--This species on account of its rapid growth was formerly much used in our area as a shade tree. It is believed that most of the trees now found along roadsides, fences, clearings and on the drier banks of streams are from seed distributed by the wind from planted trees. This species is now little used as a shade tree and is never recommended because it sheds its leaves early, and is subject to injury from disease and insects.

[Ill.u.s.tration: Plate 111.

ACER NEGUNDO Linnaeus. Box Elder. ( 1/2.)]

=1a. Acer Negundo= variety =violaceum= Kirchner. (_Rulac Nuttallii_ Nieuwland). This variety is distinguished by its glaucous twigs and by the body of the fruit being glabrous at maturity. In most instances when the bloom is rubbed from the twigs they show a purple tinge, hence the varietal name.

=Distribution.=--I have this variety in Indiana from the following counties: Brown, Ca.s.s, Elkhart, Franklin, Fulton, Hendricks, Henry, Jennings, Lagrange, Martin, Posey, St. Joseph, Vermillion and Wayne.

=2. Acer saccharnum= Linnaeus. Silver Maple. Soft Maple. White Maple.

Plate 112. Medium sized trees; bark of small trees smooth and gray, becoming on old trees reddish-brown, and freely splitting into thin scales; branchlets light to reddish-brown and generally turning upward at their tips; leaves generally about 1 dm. long, generally somewhat cordate at the base, sometimes truncate, deeply 3-lobed, each of the lateral lobes with an additional lobe below, margins of all of the lobes more or less irregular or even lobed, the two princ.i.p.al sinuses generally show a tendency to close, leaves hairy beneath when young, glabrous above and below at maturity and very glaucous beneath; flowers appear in March or April in the axils of the leaves of the previous year, the staminate and pistillate in separate cl.u.s.ters on the same or different trees; fruit on pedicels 1.5-6 cm. long, maturing in the spring or early summer, green, densely hairy while young and remaining more or less hairy at maturity, 4-7 cm. long, wings 1-2 cm. wide.

=Distribution.=--New Brunswick to Florida, west to South Dakota and south to Texas. Locally frequent to very common in all parts of Indiana.

This species is always found in wet or moist places, and in the lower Wabash bottoms in low overflow lands or in or about old sloughs it often forms the princ.i.p.al stand. It is more frequently a.s.sociated with black willow, white elm, red birch, sycamore, etc.

=Remarks.=--The silver maple has been used extensively for shade tree planting. The branches are very brittle, and ice storms sometimes break off so many branches that the tree may be badly injured. The shade trees of this species are in many parts of the state being killed by scale insects, and for this reason it should not be used. On account of its rapid growth it has also been much used for windbreaks but this practice should be discouraged and better species used.

[Ill.u.s.tration: Plate 112.

ACER SACCHARINUM Linnaeus. Silver Maple. ( 1/2.)]

=3. Acer rubrum= Linnaeus. Red Maple. Soft Maple. Swamp Maple. Plate 113.

Medium to large sized trees; bark of small trees smooth and gray, becoming dark brown on old trees, somewhat furrowed and scaly; branchlets smooth and reddish; twigs generally smooth but sometimes hairy, becoming glabrous by autumn; leaves 5-12 cm. long, 3-5 lobed, more or less cordate at the base, sometimes truncate or rounded, sinuses acute, those of 3-lobed leaves generally wider angled than those of 5-lobed ones, the lobes more or less irregularly serrate or dentate, hairy while young, glabrous above and more or less hairy beneath at maturity, glaucous beneath; flowering period March or April; flowers red or reddish, in the axils of the leaves of the previous year, the staminate and pistillate in separate cl.u.s.ters on the same or different trees; fruit maturing late in spring, on pedicels 3-8 cm. long, generally red, sometimes green, glabrous at maturity, rarely somewhat p.u.b.escent, 1.5-3.5 cm. long.

=Distribution.=--Newfoundland to Florida, west to Minnesota and south to Texas. It is found in all parts of Indiana. Its preferred habitat is that of low ground about lakes, swamps, along streams and in the "flats"