Michigan Trees Part 42

+WINTER KEY TO THE SPECIES OF AESCULUS+

a. Terminal bud about 2/3 inch long; bud-scales covered with a glaucous bloom, not conspicuously resinous; bark broken into thick plates; p.r.i.c.kly bur about 1 inch in diameter. _A.

glabra_, p. 199.

aa. Terminal bud 1-1-1/2 inches long; bud-scales conspicuously sticky-resinous, glistening; bark broken into thin plates; p.r.i.c.kly bur about 2 inches in diameter. _A. hippocastanum_, p.

197.

[Ill.u.s.tration: +Horse-chestnut+

1. Winter twig, 3/4.

2. Leaf, 1/6.

3. Leaflet, 1/2.

4. Flower, 1.

5. Fruit, 1/2.]

+SAPINDACEAE+

+Horse-chestnut+

_Aesculus hippocastanum L._

HABIT.--A handsome tree, with a height of 40-60 feet and a trunk diameter of 1-2 feet, forming a broad, conical crown. The regularly occurring branches ascend from the trunk at first, gradually bend downwards as they lengthen, and end in a thick, upturning spray.

LEAVES.--Opposite, digitately compound. Leaflets usually 7, rarely 5, 5-7 inches long, 1-1/2-2-1/2 inches broad; obovate, wedge-shaped at the base; irregularly and bluntly serrate; thick; rough, dark green above, paler beneath, turning a rusty yellow in autumn. Petioles long, grooved, swollen at the base.

FLOWERS.--May-June, after the leaves; polygamo-monoecious; large, whitish, in showy, upright, terminal thyrses 8-12 inches long; pedicels jointed, 4-6-flowered; calyx campanulate, 5-lobed; petals 5, white, spotted with yellow and red, clawed; stamens 7, thread-like, longer than the petals.

FRUIT.--October; a leathery, globular capsule about 2 inches in diameter, roughened with short spines; containing 1-3 large, smooth, l.u.s.trous, brown nuts, marked by large, pale scars.

WINTER-BUDS.--Terminal buds 1-1-1/2 inches long, acute, brownish, covered with glistening, resinous gum; inner scales yellowish, becoming 1-1/2-2 inches long in spring, remaining until the leaves are nearly half grown.

BARK.--Twigs smooth, red-brown; trunk dark brown and broken into thin plates by shallow fissures; rich in tannin, bitter.

WOOD.--Light, soft, close-grained, weak, whitish, with thin, light brown sapwood.

NOTES.--A native of Greece, extensively cultivated throughout Europe and America, where it is a favorite shade tree. A double-flowered variety, _Aesculus hippocastanum, v. flre pleno_, which bears no fruit is a common garden form.

[Ill.u.s.tration: +Ohio Buckeye+

1. Winter twig, 1.

2. Leaf, 1/6.

3. Leaflet, 1/2.

4. Flower, 2.

5. Fruit, 1/2.

6. Nut, 1/2.]

+SAPINDACEAE+

+Ohio Buckeye+

_Aesculus glabra Willd._

HABIT.--A medium-sized tree 30-50 feet in height, with a trunk not over 2 feet in diameter; usually much smaller; slender, spreading branches, forming a broad, rounded crown; twigs thick.

LEAVES.--Opposite, digitately compound. Leaflets usually 5, rarely 7, 3-6 inches long, 1-1/2-2-1/2 inches broad; ovate or oval, gradually narrowed to the entire base; irregularly and finely serrate; glabrous, yellow-green above, paler beneath, turning yellow in autumn. Petioles 4-6 inches long, slender, enlarged at the base. Foliage ill-smelling when bruised.

FLOWERS.--April-May, after the leaves; polygamo-monoecious; small, yellow-green, in terminal panicles 5-6 inches long and 2-3 inches broad, more or less downy; pedicels 4-6-flowered; calyx campanulate, 5-lobed; petals 4, pale yellow, hairy, clawed; stamens 7, with long, hairy filaments.

FRUIT.--October; a thick, leathery, p.r.i.c.kly capsule, about 1 inch in diameter, containing a single large, smooth, l.u.s.trous, brown nut. A large pale scar gives the name "Buckeye".

WINTER-BUDS.--Terminal buds 2/3 inch long, acute, resinous, brownish; inner scales yellow-green, becoming 1-1/2-2 inches long in spring and remaining until the leaves are nearly half grown.

BARK.--Twigs smooth, red-brown, becoming ashy gray; old trunks densely furrowed and broken into thick plates; ill-smelling when bruised.

WOOD.--Light, soft, close-grained, weak, whitish, with thin, light brown sapwood.

NOTES.--A native of the Mississippi River Valley. Occasionally planted in southern Michigan for ornamental purposes, but is less popular than the Horse-chestnut.

[Ill.u.s.tration: +Ba.s.swood+

1. Winter twig, 1.

2. Leaf, 1/2.

3. Cyme of flowers, with its bract, 1/2.

4. Flower, with two petals, petaloid scales and stamens removed, enlarged.

5. Stamen, enlarged.

6. Fruit, 1/2.]

+TILIACEAE+

+Ba.s.swood+

_Tilia americana L._

HABIT.--A tree usually 60-70 feet high, with a tall, straight trunk 2-4 feet in diameter; numerous slender branches form a dense, ovoid or rounded crown.

LEAVES.--Alternate, simple, 5-6 inches long, 3-4 inches broad; obliquely heart-shaped; coa.r.s.ely serrate; thick and firm; glabrous, dull dark green above, paler beneath; petioles slender, 1-2 inches long.

FLOWERS.--June-July, after the leaves; perfect, regular; yellowish white, downy, fragrant; borne on slender pedicels in loose, drooping cymes, the peduncle attached for half its length to a narrow, oblong, yellowish bract; sepals 5, downy; petals 5, creamy white; stamens numerous, in 5 cl.u.s.ters; ovary 5-celled; stigma 5-lobed.

FRUIT.--October; globose, nut-like, woody, gray, tomentose, about the size of peas.