The Slippery Elm
U. fulva, Michx.
The slippery elm is also known as the red elm and moose elm, because its wood is red and moose are fond of browsing its young shoots. In regions where moose are rarely seen, it is the small boy who browses and often utterly destroys every specimen of this valuable tree. Under the bark of young shoots a sweet substance is found, which gives the tree its common name. What man lives who in the heydey of youth has not had the spring craze for slippery elm bark, as surely as he had the fever for kite-flying and playing marbles? The trees in every fence row show the wounds of jack-knives; stripping the bark, the boys scrape from its inner surface the thick, fragrant mucilaginous cambium—a delectable substance that allays both hunger and thirst. Fortunately the bark of the limbs supplies the demand; many a veteran tree still suffers the pollarding process, serving one generation of schoolboys after another.
The inner bark, dried and ground and mixed with milk, forms a valuable food for invalids. Poultices of slippery elm bark relieve throat and chest ailments. Fevers and acute inflammatory disorders are treated with the same bark, which has passed from the list of mere home remedies to an established place on the apothecary's shelf.
How shall we tell a slippery elm tree from the American elm? By its leaf in summer. The roughness of the foliage is one of its striking characteristics. Crumple a leaf, and its surfaces grate harshly, for they are covered with stiff, tubercular hairs. The leaves are larger, often reaching seven inches in length. There is a reddish or tawny pubescence on all young shoots, and especially on the bud scales in winter. The tree itself, in winter or summer, is much more coarse than its cousin. It is also unsymmetrical in habit, each limb striking out for itself. Very often one meets a tree quite as one-sided in form as its leaf, and this without any apparent reason. But given a chance to grow without mutilation, the slippery elm attains a height of seventy feet, forming a broad, open head, in comparatively few years. It is well worth planting for its lumber and for shade.
The Rock Elm
U. Thomasi, Sarg.
The rock elm or cork elm chooses dry, gravelly upland and low heavy clay soil, on rocky slopes and river cliffs, from Ontario and New Hampshire westward through northern New York, southern Michigan to Nebraska and Missouri. It is more abundant and of largest size in Ontario and in the southern peninsula of Michigan.
Its leaf is small, thick, and firm, dark green, and turns to brilliant yellow in the autumn. Its flowers and fruits are borne in racemes. At any season, one knows this cork elm by the shaggy bark on its stout limbs that make the tree resemble a bur oak. "Rock elm" and "hickory elm" are names that refer to the hardness of the wood. The wheelwright counts it the best of all elms. Compact, with interlacing fibres, there are spring, strength, and toughness in this wood which adapt it for bridge timbers, heavy agricultural implements, wheel stocks, sills, and axe-handles. The name "cork elm" refers to the corky bark which runs out in winged ridges, even to the twigs.