Michigan Trees Part 41

_Acer platanoides L._

HABIT.--A tall, handsome tree, with a height of 40-60 feet, and a trunk diameter of 1-2 feet, having a round, spreading crown of stout branches, resembling _A. saccharum_. Twigs coa.r.s.e.

LEAVES.--Opposite, simple, 5-7 inches broad, and almost as long; thin; 5-7-lobed at maturity, lobes remotely coa.r.s.e-toothed with the teeth drawn out into filamentous points, separated by rounded, scallop-like sinuses; glabrous, bright green both sides, turning pale yellow in autumn; petioles long, slender, exuding a milky juice when cut.

FLOWERS.--May-June, before or with the leaves; dioecious; large, yellow-green, in erect, short, flat racemes; sepals 5; petals 5; stamens 8.

FRUIT.--Ripens in autumn and germinates the following spring; pendent on long stalks; large, glabrous, paired samaras, with wings 2 inches long, diverging by nearly 180.

WINTER-BUDS.--Yellow-green, red or dull red-brown; terminal bud about 1/4 inch long, broad, short-stalked, with bud-scales strongly keeled; lateral buds small, appressed; buds exuding a milky juice when cut.

BARK.--Twigs l.u.s.trous, light brown to greenish; trunk dark gray, becoming closely fissured, not scaly.

WOOD.--Moderately heavy, hard, close-grained, whitish or brownish, with white sapwood.

NOTES.--Exotic from Europe. Extensively planted in cities for its abundant shade. The roots strike deep and spread laterally, enabling the tree to hold its own in a city environment. It holds its leaves two weeks longer in autumn than do our native maples. A rapid grower.

[Ill.u.s.tration: +Sycamore Maple+

1. Winter twig, 1.

2. Leaf, 1/2.

3. Flowering branchlet, 1/2.

4. Staminate flower, enlarged.

5. Perfect flower, enlarged.

6. Fruit, 1/2.]

+ACERACEAE+

+Sycamore Maple+

_Acer pseudo-plata.n.u.s L._

HABIT.--A thrifty tree 50-60 feet high, with a trunk diameter of 2-3 feet; the crown roundish, spreading.

LEAVES.--Opposite, simple, 4-7 inches across, and as long as broad; thick; pentagonally 5-lobed, the lobes more or less ovate, separated by very narrow, acute sinuses extending about half-way to the midrib, the lobes coa.r.s.ely and irregularly blunt-serrate, crenate-serrate, or slightly lobed; upper surface dark green and shining, somewhat wrinkled, but paler dull green and glaucous beneath; petioles long, stout.

FLOWERS.--April, before the leaves; polygamo-monoecious; large, greenish yellow, in pendent racemes of umbellate cymes of about three each; sepals 5; petals 5; stamens 8, hairy; ovary hairy.

FRUIT.--Ripens in autumn and germinates the following spring; pendent on long stalks; large, glabrous, paired samaras, with wings 1-1/2 inches long, diverging at about a right angle.

WINTER-BUDS.--Bright green; terminal bud 1/4-1/2 inch long, ovoid to subglobose, blunt, with bud-scales more or less keeled; lateral buds small, divergent.

BARK.--Twigs l.u.s.trous, brown or gray, becoming slate colored on the branches; trunk gray or brownish, smooth or flaking off in short scales.

WOOD.--Moderately heavy, hard, compact, brownish, with white sapwood.

NOTES.--Exotic from Europe. Much planted in our cities, where it is thrifty, but short-lived. The crown is rather too broad for planting anywhere except on our widest streets. The leaves last two weeks longer in autumn than do those of our native maples.

[Ill.u.s.tration: +Boxelder. Ash-leaved Maple+

1. Winter twig, 1.

2. Leaf, 1/2.

3. Staminate flowering branchlet, 1/2.

4. Staminate flower, enlarged.

5. Pistillate flowering branchlet, 1/2.

6. Pistillate flower, enlarged.

7. Fruit, 1.]

+ACERACEAE+

+Boxelder. Ash-leaved Maple+

_Acer negundo L._ [_Negundo aceroides Muench._]

HABIT.--A st.u.r.dy little tree 30-50 feet high, with a trunk diameter of 1-2 feet. Trunk often divides near the ground into several stout, wide-spreading branches, forming a broad, unsymmetrical, open crown.

LEAVES.--Opposite, pinnately compound. Leaflets 3-5 in number, 2-4 inches long, 1-1/2-2-1/2 inches broad; ovate or oval; nearly entire, irregularly and remotely coa.r.s.e-toothed above the middle, or sometimes 3-lobed (often giving the leaflet a jagged outline); apex acute, base variable; glabrous or somewhat p.u.b.escent at maturity, with prominent veins. Petioles slender, 2-3 inches long, the enlarged base leaving prominent crescent-shaped scars partly surrounding the winter-buds.

FLOWERS.--April, before or with the leaves; dioecious; small, yellow-green; the staminate in cl.u.s.ters on long, thread-like, hairy pedicels; the pistillate in narrow, drooping racemes; calyx hairy, 5-lobed; corolla 0; stamens 4-6; ovary p.u.b.escent.

FRUIT.--Early summer, but hanging until late autumn or early spring; narrow, flat, winged samaras, in pairs, cl.u.s.tered in drooping, racemose cl.u.s.ters.

WINTER-BUDS.--Terminal bud 1/8-1/4 inch long, acute, inclosed in two dull red scales, often h.o.a.ry or minutely p.u.b.escent; lateral buds obtuse, appressed.

BARK.--Twigs greenish to purple, glaucous; trunk pale gray or light brown, deeply cleft into broad ridges.

WOOD.--Light, soft, close-grained, weak, creamy white, with thick, hardly distinguishable sapwood.

DISTRIBUTION.--Lower Peninsula as far north as Saginaw Bay.

HABITAT.--Banks of streams and borders of swamps. Prefers deep, moist soil.

NOTES.--Accommodates itself to almost any situation. Easily transplanted.

Much planted for shade and ornament. Fast-growing, but short-lived.

+SUMMER KEY TO THE SPECIES OF AESCULUS+

a. Leaflets usually 5; foliage ill-smelling when bruised; bark broken into thick plates; p.r.i.c.kly bur about 1 inch in diameter. _A. glabra_, p. 199.

aa. Leaflets usually 7; foliage not ill-smelling when bruised; bark broken into thin plates; p.r.i.c.kly bur about 2 inches in diameter. _A. hippocastanum_, p. 197.