The twigs and branchlets are armed with straight or slightly curved sharp, strong spines, sometimes as much as 1 inch in length which remain attached to the outer bark for many years. The _bark_ is dark brown and divides into strips as the tree grows older. The _leaves_ are pinnate, or featherlike, from 6 to 10 inches in length, consisting of from 7 to 19 oblong thin leaflets. The _flowers_ are fragrant, white or cream-colored, and appear in early spring in graceful pendent racemes. The _fruit_ is a pod from 3 to 5 inches long containing 4 to 8 small hard seeds which ripen late in the fall. The pod splits open during the winter, discharging the seeds. Some seeds usually remain attached to each half of the pod; the pod thus acts as a wing upon which the seeds are borne to considerable distances before the strong spring winds. The _wood_ is yellow in color, coarse-grained, very heavy, very hard, strong, and very durable in contact with the soil. It is used extensively for fence posts, poles, tree nails, insulator pins and occasionally for lumber and fuel. The tree is very rapid in growth in youth but short-lived. It spreads by underground shoots and is useful for holding and reclaiming badly gullied lands. The usefulness of the black locust is, however, very greatly limited by the fact that it is subject to great damage from an insect known as the locust borer. +TREE OF HEAVEN+ _Ailanthus altissima_ Swingle THIS tree is a native of China but planted in Illinois because of its tropical foliage. It has escaped and become naturalized. It is a handsome, rapid-growing, short-lived tree, attaining a height of 40 to 60 feet, and a trunk diameter of 2 to 3 feet. Its crown is spreading, rather loose and open. The twigs are smooth and thick with a large reddish-brown pith. The _winter buds_ are small, globular and hairy, placed just above the large leaf-scars. [Illustration: TREE OF HEAVEN Twig, one-half natural size. Leaf and fruit, one-fourth natural size.] The _leaves_ are alternate, pinnately compound and one to three feet long. The leaflets number from 11 to 41, are smooth, dark green above, paler beneath, turning a clear yellow in autumn. The _flowers_ appear soon after the leaves are full grown, on different trees, borne in large upright panicles. They are small yellow-green in color with 5 petals and 10 stamens. The staminate flowers have a disagreeable odor. The _fruit_, ripening in October but remaining on the tree during the winter, is a one-seeded samara, spirally twisted, borne in crowded clusters. The tree of heaven is useful for landscape planting, succeeding in all kinds of soils and all kinds of growing conditions. It makes a rapid showing and is practically free from all diseases and insect injury. +SMOOTH SUMAC+ _Rhus glabra_ L.