Michigan Trees Part 32

3. Vertical section of twig, summer bud and leaf petiole, enlarged.

4. Leaf, 3/8.

5. Flowering branchlet, 1/2.

6. Staminate flower, enlarged.

7. Pistillate flower, enlarged.

8. Fruit, 3/8.

9. Achene, enlarged.]

+PLATANACEAE+

+Sycamore. b.u.t.ton-wood. b.u.t.tonball-tree+

_Plata.n.u.s occidentalis L._

HABIT.--A large tree 70-100 feet high, with a trunk diameter of 3-8 feet; commonly dividing near the ground into several large secondary trunks, forming a broad, open, irregular crown of ma.s.sive, spreading branches.

LEAVES.--Alternate, simple, 5-10 inches long and broad; broadly ovate in outline; more or less 3-5-lobed by broad, shallow sinuses, the lobes sinuate-toothed; thin and firm; bright green above, paler beneath, glabrous both sides; petioles stout, p.u.b.erulous, 1-2 inches long.

FLOWERS.--May, with the leaves; monoecious; borne in dense heads; the staminate dark red, on short, axillary peduncles; the pistillate greenish, on long, slender, terminal peduncles; sepals 3-6, minute; petals 3-6, minute; stamens 3-6, usually 4; styles long, incurved, red.

FRUIT.--October, persistent on the limbs through the winter; brown heads about 1 inch in diameter, on slender, glabrous stems 3-6 inches long.

WINTER-BUDS.--Terminal bud absent; lateral buds 1/4-3/8 inch long, conical, blunt, l.u.s.trous, pale brown; forming in summer within the petiole of the leaf.

BARK.--Twigs pale green and tomentose, becoming smooth, dark green, finally grayish; thick, red-brown on the trunk and broken into oblong, plate-like scales, separating higher up into thin plates which peel off, exposing the greenish or yellowish inner bark.

WOOD.--Heavy, tough, hard, rather weak, coa.r.s.e-grained, difficult to split, light red-brown, with thick, darker colored sapwood.

DISTRIBUTION.--Lower Peninsula as far north as Roscommon County.

HABITAT.--Prefers rich bottom-lands along the borders of rivers and lakes.

NOTES.--Rapid of growth. Bears transplanting well. Often planted as a shade tree. Fungous diseases disfigure it seriously.

+SUMMER KEY TO THE SPECIES OF PYRUS+

a. Leaves simple; fruit a light green pome an inch or more in diameter; branches contorted, bearing many short, spur-like branchlets. _P. coronaria_, p. 145.

aa. Leaves compound; fruit berry-like, 1/4 inch in diameter, bright red; branches not contorted, not bearing many short, spur-like branchlets. _P. americana_, p. 147.

+WINTER KEY TO THE SPECIES OF PYRUS+

a. Bundle-scars 3 or in 3 compound, but distinct groups; buds 1/8-1/4 inch long; branches contorted, bearing many short, spur-like branchlets; fruit a pome an inch or more in diameter, light green. _P. coronaria_, p. 145.

aa. Bundle-scars 4-many in a single U-shaped line, not forming 3 distinct groups; buds about 1/2 inch long; branches not contorted, not bearing many short, spur-like branchlets; fruit berry-like, 1/4 inch in diameter, bright red. _P. americana_, p. 147.

[Ill.u.s.tration: +Sweet Crab. American Crab+

1. Winter twig, 1.

2. Portion of twig, enlarged.

3. Leaf, 3/4.

4. Flowering branchlet, 1/2.

5. Vertical section of flower with petals removed, 1/2.

6. Fruit, 1/2.]

+ROSACEAE+

+Sweet Crab. American Crab+

_Pyrus coronaria L._ [_Malus coronaria Mill._]

HABIT.--Often a bushy shrub, but frequently a small tree 15-25 feet high, with a trunk 8-12 inches in diameter; forming a broad, rounded crown of rigid, contorted branches bearing many short, spur-like branchlets.

LEAVES.--Alternate, simple, 3-4 inches long, almost as broad; ovate to nearly triangular; sharply and deeply serrate, sometimes lobed; membranaceous; bright green above, paler beneath, glabrous both sides; petioles long, slender, often with two dark glands near the middle.

FLOWERS.--May, after the leaves; perfect; 1-1/2-2 inches across; very fragrant; borne on slender pedicels in 5-6-flowered umbels; calyx urn-shaped, 5-lobed, tomentose; petals 5, rose colored to white; stamens 10-20; ovary hairy; styles 5.

FRUIT.--October; a depressed-globose pome, 1-1-1/2 inches in diameter, pale green, very fragrant, with a waxy surface.

WINTER-BUDS.--Terminal bud 1/8-1/4 inch long, obtuse, bright red; lateral buds smaller.

BARK.--Twigs at first h.o.a.ry-tomentose, becoming glabrous, red-brown; thin, red-brown, breaking into longitudinal fissures on the trunk.

WOOD.--Heavy, rather soft, close-grained, weak, red-brown, with thick, yellow sapwood.

DISTRIBUTION.--Southern portion of the Lower Peninsula as far north as Roscommon County.

HABITAT.--Rich, moist, but well-drained soil in thickets and along streams.

NOTES.--An excellent ornamental tree or shrub for small gardens and shrubberies. The fruit is sometimes gathered for making preserves.

[Ill.u.s.tration: +Mountain Ash+

1. Winter twig, 1.

2. Portion of twig, enlarged.

3. Leaf, 1/3.

4. Vertical section of flower, enlarged.

5. Portion of a fruiting cyme, 1.]

+ROSACEAE+