FAMILY BETULACEÆ
1. Genus OSTRYA Scop.
SMALL trees with very hard wood and scaly bark. Leaves simple, alternate, ovate, deciduous. Flowers small, monœcious, both in catkins. Fruits conical, hop-like, of many nuts, each in an inflated sac.
KEY TO SPECIES
A. Leaves 3 to 5 inches long, tapering to point: (O. Virginiana) HOP HORNBEAM
AA. Leaves 1 to 2 inches long, rounded at point: (O. Knowltoni) IRONWOOD
2. Genus CARPINUS, Linn.
Small tree, with smooth, grey bark, showing swellings like veins. Leaves simple, alternate, oblong-lanceolate. Flowers, both sorts in aments, monœcious. Fruit, paired nutlets, each with a 3-lobed wing: (C. Caroliniana) HORNBEAM
The hornbeams, or ironwoods, are little trees hiding in the shadows of the forest. They are of slow growth; their wood is very hard. They bear their flowers in catkins, the two sorts upon the same tree: the staminate axillary, the pistillate terminal. The seeds are formed for wind distribution. Birches, alders, that shrubby genus Corylus, the hazels, are associated by family characters. America has five of the six genera that compose Family.
As a rule the hardest woods come from tropical forests. Witness the lignum vitæ, hardest of woods, which grows in Florida, the West Indies, and northern South America; the mahogany of Central America; the rosewood from Brazil; and the ebony from Ceylon, tropical Africa and Cuba. Northern forests, too, furnish some species with exceptionally hard wood. The hornbeams are the best proof of this statement; the strength, hardness and flexibility of their wood rival steel. In durability they excel the best oak.
The name, ironwood, is locally given to any tree whose wood is hard.
1. GENUS OSTRYA, Scop.
Hop Hornbeam, Ironwood (Ostrya Virginiana, Willd.)—Small, slender tree, with round head of stiff, wiry branches. Bark greyish brown, furrowed into narrow, scaly ridges, which break into small, oblong plates. Wood reddish brown, heavy, cross grained, tough, strong and hard to work. Buds lateral, ovate, acute, small, brown. Leaves ovate, acuminate, sharply and doubly serrate, 3 to 5 inches, thin, tough, dull yellow-green above, paler beneath; yellow in autumn; petioles short, hairy. Flowers with leaves, April and May, monœcious; staminate in catkins formed previous season; pistillate erect, loose catkins, each flower surrounded by three united bracts. Fruit a hop-like cluster of inflated bags, formed of bracts, each containing a hard little seed. Preferred habitat, shady forest ground. Distribution, Nova Scotia to Black Hills; south to Florida and Texas. Uses: Wood used for mallets, levers and tool handles. Desirable for ornamental planting, but rarely used.
The hop hornbeam looks like a relative of the birches. Its leaves convey this impression, and slender limbs in winter bear green catkins that cluster in threes on the ends of twigs and wait for spring, just as the birch catkins do.
The bark of this hornbeam is thin and scales off in narrow strips whose surfaces are covered with squarish scales. The pale colour and the stripping of the bark reminds us of the shell-bark—its shaggy strips reduced to a small scale. Among the branches the bark is smooth and close, and the twigs look like fine wires, springing out at right angles from the stem.
In spring the staminate catkins swing out, even as the birch flowers do, but the pistillate clusters have to be looked for. The red, forked tongues thrust out for pollen may be seen at the ends of leafy side shoots. Here the midsummer shows a hop-like cluster of little pale green sacs, each with a shining seed inside.
The hop hornbeam is of a retiring disposition, preferring to hide in the shadows of taller trees. But there is nothing dark or funereal about it. The leaves, bright and green, are held out in level platforms where they can get the sunbeams that trickle down to them. Then comes summer, and the pale green “hops” make the tree a centre that seems to shed light into dark places. The little hop tree, Ptelea trifoliata, is shining in its corner, and at a short distance the two trees might be confused. Each one is a blessed sight on a hot day, for pale green against dark green is always a cool colour scheme.
In the late autumn, after the leaves turn yellow and fall, the hops still hang, grudgingly giving up one little seed balloon after another to the insistent wind. There is likely to be a long sail for each one, and perhaps more than one, for until the bag is punctured and the seed covered, the wind gives it no rest.
The wood of the hop hornbeam is vexatious stuff for the turner, and whoever else tries tool upon it. But once it takes shape it lasts indefinitely. Sled stakes, levers, rake teeth, tool handles, wedges, do not soon need replacing if made of this material. It is equally satisfactory when used for fence posts.
The parks about Boston have beautiful specimens of the hop hornbeam, showing that its merits as an ornamental tree are being recognised by the best judges. The next step will be its increasing popularity for private grounds.
The Western Ironwood (O. Knowltoni), which was discovered in Arizona but a few years ago, is smaller in every way than the Eastern species, but every trait proclaims it a hop hornbeam. The leaves, catkins and hops are short and blunt pointed. The protective pubescence which belongs to desert plants is on the young shoots and the leaves and fruits of this tree. Its limbs are often gnarled, but it forms a rounded symmetrical top, and is sometimes 30 feet high.
The tree is probably one of the rarest in the country, for as far as known it has not been found except in one locality, where it has formed a considerable grove. How this species has been cut off from its near relative in the East is a problem worthy of investigation.
2. GENUS CARPINUS, Linn.
American Hornbeam, Blue Beech (Carpinus Caroliniana, Walt.)—Small, shapeless tree with irregular limbs, often pendulous, and slender, wiry twigs. Bark furrowed at base of trunk on old trees; smooth, bluish grey above, swollen as by veins underneath the bark; twigs brown. Wood light brown, heavy, hard, strong, fine, hard to work. Buds all lateral, ovate, small, brown. Leaves ovate-oblong, long pointed, irregularly doubly serrate, often unequal at base, dull green, pale beneath, orange or scarlet in autumn; hairy petiole and veins. Flowers monœcious, with leaves, in April; staminate catkins, 1 ½ inches long, pendulous, lateral; pistillate flowers in racemes, terminal, loose flowered, with forked red stigmas under green scales. Fruit racemed, hard nutlets in pairs, each supported by a large, leaf-like, 3-lobed bract. Preferred habitat, swampy rich soil near streams, in shade of taller trees. Distribution, Georgian Bay (southern Canada) to Florida; west to Minnesota and Texas; also in Mexico and Central America. Uses: Curious and interesting tree for planting along watercourses, but rarely seen in landscape gardening. Wood used for tool handles, levers and ox yokes.
The American hornbeam has no “hop” in its name because its fruit has none. Each little seed in the terminal cluster has a mate on the other side of the stem, and all summer they have grown close together, back to back, generally crowding for more room. Each seed sits in the prow of a little boat, shaped like a red maple leaf, but hollowed like a scallop shell. The wind finally loosens the hold of each, and for a time seed and boat hang by a thread. This breaks at last, and the little nut sails off at the will of the wind, to grow, if it falls in wet ground.
This hornbeam resembles Ostrya in many particulars—its leaves, its flowers, its delicate wiry twigs, its foliage, and the hardness of its wood. It grows, too, in the shadows of other trees. The bark it is that sets the trees apart. This tree has bark like a young beech, a thin, smooth, blue-grey rind, that has strange flutings or vein-like swellings coursing up the trunk and out on the larger limbs. They remind one of the veins of a blacksmith’s sinewy arm, or an athlete’s. A trunk a foot in diameter at the base generally shows a few furrows, and some minor roughness near the ground, but above, the smoothness is unbroken.
The hornbeam grows often in thickets, sometimes as scattered single trees, in marshy ground and along streams. It is a pretty tree, with blue-green leaves that turn to orange and scarlet in the autumn. It is coming into notice as an ornamental tree, now that people are learning that the best way to make a park is to do less levelling and filling, and plant in the lower ground trees and plants that choose such situations naturally.
The anguish of working in this wood was experienced by the early colonists, who appreciated its value. “The New England Prospect” says: “The Horne bound tree is a tough kind of wood that requires so much paines in riving as is almost incredible, being the best for to make bolles and dishes, not being subject to cracke or leake.” Heads of beetles, stocks, mill cogs, yoke timbers, levers—for such uses it is ideal wood.
The European Hornbeam (Carpinus Betulus, Linn.) ranges from Scandinavia and England to the Caucasus, and is a beautiful tree of no small note. The “hornbeams” of ancient ox yokes wore indefinitely, becoming as hard and smooth as horn. The trees grow in cold, forbidding situations, where most trees fail, and so serve as windbreaks and as covers of barren clay soil. The wood makes excellent fuel and charcoal, beside its special uses to the turner. In the old days of formal gardens, the hornbeam was popular, for it suffered itself to be clipped with as much patience as the linden, the beech or the yew. It was a famous hedge tree. The Germans made fences by planting rows of the saplings leaning so that each two plants formed a cross. The bark was scraped at the point of intersection, and then the two were bound together with straw, until they grew fast to each other. Careful pruning made of this in a short time a beautiful and impenetrable wall. Miles of this fencing were seen in Evelyn’s day. The Germans also planted the trees near the gates of the great cities, training their branches to cover arbours “for convenience of the people to sit and solace in.” Travellers in Europe will find the hornbeam still much used as in earlier centuries.
China, Japan and India have native hornbeams; there are nine or ten species in all. The race is old—the rocks show fossils of extinct species that once inhabited western America.