572 PLANE TREE eccentricity and the inclination of the solar system regarded as a whole remain constant. Not the star sphere itself is more unchanging than the position of that circle upon it which marks the position of the well named " fixed plane " of the planetary system. PLANE TREE, a common name for species of the genus platanus (Gr. Tr/lar^c, broad), in this country called buttonwood and buttonball, American Plane Tree (Platanus occidentalis). and incorrectly sycamore. The genus standing alone in its family (platanacecv), the charac- ters 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 ster- ile 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 especial- ly 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 rapid- ity. 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, trun- cate 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 pro- duce 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 shed- ding of the down already referred to makes it objectionable near dwellings. The wood is hard, firm, and close, of a reddish tint, variega- ted 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 some- times 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, California Plane Tree (Platanus racemosus). 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 Eu- rope ; 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 i?
Page:The American Cyclopædia (1879) Volume XIII.djvu/588
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