Plane Tree, a common name for species of the genus platanus (Gr. , broad), in this country called button wood and buttonball, and incorrectly sycamore. The genus standing alone in its family (platanacece), the characters are the same for both. The tree has a flaking bark, alternate-petioled, large, palmate-ly nerved leaves, with sheathing stipules; the flowers are monoecious, in separate spherical heads, and without calyx or corolla; the sterile flowers consist of numerous stamens with club-shaped scales intermixed; the fertile have inversely pyramidal ovaries, also intermingled with scales, which by some are regarded as arrested stamens; the fruit is a club-shaped, one-seeded nutlet, with bristly down at the base. Only five species of platanus are known, all but one of which are North American. The common plane or buttonwood (P. occidentalis), called in England the occidental plane, extends from New England to Florida, and westward as far as the Rocky mountains, being especially abundant in the states west of the Allegha-nies, and attains its greatest size in the valley of the Ohio and its tributaries. It likes a moist rich soil, in which it grows with great rapidity.
It is the grandest of our deciduous trees, attaining over 100 ft. in height and a diameter of trunk of 10 to 15 ft. or more. The leaves are 5 or 6 in. long and 7 or 8 in. broad, truncate or heart-shaped at base, the margin lobed or angled; in autumn they turn pale yellow, and when they drop disclose the bud which has been concealed beneath the hollowed base of the petiole; the stipules of this tree are large, conspicuous, and leaf-like, usually united to form a sheath around the stem; the young shoots, leaves, and stipules are covered with a fine thick down, which falls off as these parts become older, and often floats in the air in such quantities as to irritate the air passages and produce a disagreeable and sometimes persistent cough in those who inhale it. The fertile heads or button-balls in this species are solitary. The branches are horizontal; the outer bark of the trunk flakes off in large patches, and sometimes entirely, exposing a surface as white as that of the white birch. As an ornamental tree its remarkably rapid growth and abundant shade are in its favor; but it is very large, and has become much disfigured by having its branches distorted by a malady attributed both to insects and to the winter-killing of the unripened wood of the previous season; and the shedding of the down already referred to makes it objectionable near dwellings.
The wood is hard, firm, and close, of a reddish tint, variegated by a silver grain, but it is not much used. - The California plane tree is named P. race-mosus by Nuttall, on account of its bearing its fertile flowers in racemes, which gives the tree a striking appearance when in fruit; the balls are strung to the number of three to five at equal distances upon a slender stalk which is 9 in. long and pendulous with their weight; the leaves are deeply divided into five, or sometimes only three lobes, and are covered upon the under side with a persistent whitish down, so close as to have the appearance of a piece of woollen cloth; the young branches, petioles, and flower stalks are also hairy. - The plane tree of ancient history, so popular with the Romans that it is said to have been nourished with wine, is P. orientalis, a native of various eastern countries, and much cultivated in Europe; though hardy, it is little planted in this country; it is closely related to our native plane, but its leaves are more deeply lobed, appear later in spring, and become smooth sooner, and the balls are larger. It does not make quite so large a tree as ours, but it is entirely free from disease.
There are several varieties, one of which, var. acerifolia, so closely resembles P. occidentalis as to be sold "for it in England. The wood of the oriental plane, being hard, close-grained, and capable of a fine polish, is much valued for furniture and joinery, and in the East is used in ship building. The remaining species are P. Lindeni, very near P. occidentalis, and P. M'exicana, which has two balls upon a peduncle 5 or 6 in. long, both natives of Mexico. - The planes may be multiplied by cuttings and by layers, but they are usually propagated from the seed.
American Plane Tree (Platanus occidentalis).
California Plane Tree (Platanus racemosus).