Part 52

BARK.--Twigs lustrous, brown, becoming dark or grayish brown; red-brown, deeply fissured, with a scaly surface on old trunks.

WOOD.--Heavy, hard, coarse-grained, weak, dark red-brown, with thin, lighter colored sapwood.

DISTRIBUTION.--Valleys of the Grand and Raisin Rivers and southward.

HABITAT.--Prefers the borders of streams and rich bottom-lands, often in the shade of other trees.

NOTES.--A rapid grower. Hardy within its range. Can be transplanted with success only when very young. Plants begin to produce flowers freely when 4-5 years old. Much used in landscape gardening.

1. Winter twig, × 1. 2. Vertical section through lateral buds, enlarged. 3. Leaf, × 1/2. 4. Raceme of flowers, × 1/2. 5. Flower, with part of corolla removed, enlarged. 6. Fruit, × 1/2.]

+LEGUMINOSAE+

+Locust. Black Locust+

Robinia pseudo-acacia L.

HABIT.--A tree 50-75 feet high, with a trunk diameter of 2-3 feet; forming a narrow, oblong crown of irregular, more or less contorted branches.

LEAVES.--Alternate, compound, 8-14 inches long. Leaflets 7-21, short-petiolate, 1-2 inches long, about one-half as broad; ovate to oblong-oval; entire; very thin; dull dark green above, paler beneath, glabrous both sides. Petioles slender, pubescent.

FLOWERS.--May-June, after the leaves; perfect; showy and abundant; very fragrant; borne on slender pedicels in loose, drooping racemes 4-5 inches long; about 1 inch long; calyx short, bell-shaped, 5-lobed, hairy; corolla papilionaceous, white, 5-petaled; stamens 10.

FRUIT.--Late autumn, but persistent on the tree through the winter; a smooth, dark brown, flat pod 3-4 inches long, containing 4-8 small, flattish, brown seeds.

WINTER-BUDS.--Terminal bud absent; lateral buds minute, 3-4 superposed, partially sunken within the leaf-scar, rusty-hairy.

BARK.--Twigs smooth, green, more or less rough-dotted at first, becoming red-brown and armed with prickles; dark red-brown and thick on old trunks, deeply furrowed into firm, sinuous ridges.

WOOD.--Heavy, very strong and hard, close-grained, very durable in contact with the soil, brown, with very thin, pale yellow sapwood.

NOTES.--Native to the Appalachian Mountains, but much planted in Michigan for ornamental and economic uses. Very rapid of growth in youth. Short-lived. Seriously attacked by borers. Spreads by underground shoots.

1. Winter twig, × 1. 2. Leaf, × 1/8. 3. Leaflet, × 1/2. 4. Staminate inflorescence, × 1/4. 5. Staminate flower, enlarged. 6. Pistillate flower, enlarged. 7. Fruit, × 1.]

+SIMARUBACEAE+

+Ailanthus. Tree of Heaven+

Ailanthus glandulosa Desf.

HABIT.--A handsome, rapid-growing, short-lived tree, attaining a height of 50-70 feet and a trunk diameter of 2-4 feet, with a spreading, rather loose and open crown and a coarse, blunt spray.

LEAVES.--Alternate, pinnately compound, 1-3 feet long. Leaflets 11-41 in number, 2-6 inches long and about one-third as broad; ovate-lanceolate; entire with the exception of two or more coarse, glandular teeth at the base; glabrous, dark green above, paler beneath, turning a clear yellow in autumn or falling without change; ill-scented. Petioles smooth, terete, swollen at the base.

FLOWERS.--June, when the leaves are full grown; polygamo-dioecious; small, yellow-green, borne in upright panicles 6-12 inches or more in length; calyx 5-lobed; petals 5, greenish, hairy; stamens 10. Staminate flowers ill-scented, pistillate almost free from odor.

FRUIT.--October; 1-celled, 1-seeded samaras, spirally twisted, reddish or yellow-green, borne in crowded clusters.

WINTER-BUDS.--Terminal bud absent; lateral buds about 1/8 inch long, subglobose, brownish, downy.

BARK.--Twigs yellowish to red-brown, velvety-downy; thin, grayish and shallowly fissured on old trunks.

WOOD.--Soft, weak, of coarse and open grain, pale yellow, satiny, with thick, lighter colored sapwood.