MAPLE. Maples and the sycamore are species of Acer,. suborder .Acerinex, order Sapindacem. The genus includes about fifty species, natives of Europe, North America, North Asia, especially the Himalayas and Japan (Benth. and Hook., Gen. Pl., i. 409). Maples are for the most part trees with palmately-lobed leaves. The flowers are in corymbs or racemes, - the lowermost mostly male, the terminal bisexual. The fruit is a two-winged " samara."
The earliest known maples occur in the Miocene strata of Oeningen, where nineteen species have been discovered, --a greater number than occurs in any one district at the present day (Lyell's El. of Geol., 6th ed. p. 250). A typical species appears to have been Acer trilobatuna, Heer (Flora Tert. Hely., pl. 114). This had many marked varieties, of which leaves, flowers, and fruit have all been discovered. The foliage was even attacked by a fungus, Rhytisnia incluratuni, Heer, just as the sycamore is now by R. acerinum, which forms black spots on the leaves.
The common maple, A. campestre, L., is the only species indigenous to Great Britain. This and the sycamore were described by Gerard in 1597 (Herball, p. 1299), the latter being " a stranger to England." Many species have been introduced, especially from Japan, for ornamental purposes. The following are more especially worthy of notice.
European. Species. - Aeer campestre, L., the common maple, is common in hedgerows, but not often seen as a tree (see, however, Loudon, Arboretum, vol, i. p. 430). Loudon gives four varieties, - the downy-fruited, the variegated, the hill-inhabiting, and the Austrian. It occurs in northern Europe, the Caucasus, and northern Asia. The wood is excellent fuel, and makes the best charcoal. It is compact, of a fine grain, sometimes beautifully veined, and takes a high polish. Bence it has been celebrated from antiquity for tables, kc. The wood of the roots is frequently knotted, and valuable for small objects of cabinet work. The young shoots, being flexible and tough, are employed in France as whips. A. psendo-Platanns, L., the sycamore, or great maple, is a handsome tree of quick growth, with a smooth bark. The -leaves are large, with finely acute and serrated lobes, aflbrding abundant shade. Its longevity is from one hundred and forty to two hundred years. 1 t is found in variook parts of Europe in wooded mountainous situations. The wood when young is white, but old heart-wood is yellow or brownish. Like the common maple it is hard and takes a high polish. It is much prized by wheelwrights, cabinetmakers, sculptors, ke., on the Continent, while knotted roots are used for inlaying. Sugar has been obtained from the sap of tins as from other species, the most being one ounce from a quart of sap. The latter has also been made into wine in the Highlands of Scotland. There are many varieties, the variegated and cut-leaved being the most noticeable (see Card. Citron., 1881, p. 229). For remarkable variations in the number of cotyledons arising from fusion, see a paper by the late Prof. J. S. 1-lenslow in Mag. Nat. Mist., vol. v. p. 346. A. Pt«tahoides, L., the Norway maple (Loudon, 1.c., p. 408 ; Gard. Citron., 1881, p. 564), is met with from Norway to Italy, Greece, central and south 'Russia. It was introduced into Britain in 1683. It is a lofty tree (from 40 to 70 feet), resembling the sycamore, but with yellow flowers, and more spreading wings to the fruit. There are several varieties. The wood is used for the same purposes as that of the sycamore. Sugar has been made from the sap in Norway and Sweden. The leaves of this species, in common with those of the sycamore especially, and perhaps all others, are liable to produce honeydew, which appears to be extravasated cell-sap. The present writer suggests that the starch formed in the leaves may be rapidly converted into sugar, which is then condensed on the surface of the leaf under excessive transpiration.
Asiatic Species. - Thirteen species are described by Hiern, chiefly in the temperate Himalayas (Flor. of Brit. India, p. 692 ; see also Brandis, For. Fl., 110). The wood of some species is used, as that of A. lazigatuni, Wall., for building ; that of A. emsizon, Wall., being soft, inferior drinking cups are made of it ; while that of A. pietam, Thunb., is white, light, and fine-grained.
Japanese Species. - Species, and many varieties, especially of A. palatal ant, Thunb., generally known as polymorphion, with variously laciniated and more or less coloured foliage, have lately been introduced as ornamental shrubs. The original species was introduced in 1832. The branches and corolla are purple, the fruit woolly. The foliage of the typical form is bright green with very pointed lobes. It occurs in the central mountains of Nippon and near Nagasaki. Beautiful varieties have been introduced nnder the names A. P. anapelopsifolium, atropurpureum, dissection, &c. They are remarkable for the coppery purple tint that pervades the leaves and young growths of some of the varieties (for figs., see Catalogue of Hardy Trees, &c., by Messrs 'Witch). Of other Japanese species, A. rufinerve, Sieb. and Zucc., with the habit of the sycamore, from Nippon ; A. distylum, Sieb. and Zucc., bearing leaves without lobes ; A. diabolieunt, BI., with large plane-like leaves, from Nippon ; and A. earpinifolium, Sieb. and Zucc., with foliage resembling that of the hornbeams, are especially worthy of note.
North American Species. - A. saeeluzrinnm, L., the sugar, rock, or bird's-eye maple, was introduced in 1735. It sometimes attains to 70 or even over 100 feet, more commonly 50 to 60 feet. It is remarkable for the whiteness of the bark. The wood is white, but acquires a rosy tinge after exposure to light. The grain is fine and close, and when polished has a silky lustre. The timber is used instead of oak where the latter is scarce, and is employed for axle-trees and spokes, as well as for Windsor chairs, &e. it exhibits two accidental forms in the arrangement of the fibres, an undulated One like those of the curled maple (A. rubrum), and one of spots which gives the name bird's-eye to the wood of this species. Like the curled maple, it is used for inlaying mahogany. It is much prized for bedsteads, writing desks, shoe lasts, &c. The wood forms excellent fuel and charcoal, while the ashes are rich in alkaline principles, furnishing a large proportion of the potash exported from Boston and New York. Sugar is principally extracted from this species, the sap being boiled and the syrup when reduced to a roper consistence run into moulds to form cakes. Trees growing in low and moist situations afford the most sap but least sugar. A cold north-west wind, with frosty nights and sunny days in alternation, tends to incite the flow, which is inure abundant during the day than the night. A thawing night is said to promote the flow, and it ceases during a south-west wind and at the approach of a storm ; and so sensitive are the trees to aspect and climatic variations that the flow of sap on the south and net side has been noticed to be earlier than on the north and west side of the same tree. The average quantity of sap per tree is from see Loudon, 1.c., p. 413 ; and Gard. Chron. 1878, p. 137.
A. rubrum, L., the rcd-flowering or scarlet maple, is a middle-sized tree, and was introduced in 1656. It is the first tree to blossom in spring in North America. The wood, like that of other species, is applicable to many purposes, as for the seats of Windsor chairs, turnery, &e. The grain in very old trees is sometimes undulated, which suggested the name of curled maple, and gives beautiful effects of light and shade on polished surfaces. The most constant use of curled maple is for the stocks of fowling pieces and rifles, as it affords toughness and strength combined. with lightness and elegance. The inner bark is dusky red. On boiling, it yields a purple colour which with sulphate of iron affords a black dye. The wood is inferior to that of the preceding species in strength and as fuel. Sugar was made from the sap by the French Canadians, but the production is only half as great as that from the sugar maple (Michaux). In Britain it is cultivated as an ornamental tree, as being conspicuous for its flowers in spring, and for its red fruit and foliage in autumn. A. macrophyllton, Pursch., furnishes material for hats, baskets, mats, &c., from its inner bark, and the sap gives sugar. A. Pursch., of California, has a fine, white, tough wood, which takes a good polish.
For description of other species of North America, sec Gard. C1ron.,11,i nava. s.e. " Accr ; Sargent's Cal. of F. Trees of Amer.; Loud. n, 405 sq.; Gray's Manual of But., p. 54. ((t. II.)