175 



BUTTONWOOD. 



Platanus occidentalis, Linnaeus. 



FAMILY AND GENUS DESCRIPTION The Plane Tree family, Platanaceae, comprises only 

 1 genus, Plutanus, with about 7 species, 3 of which are native to the United States and 1 to 

 Pennsylvania. In addition to the 1 species native to this State, the Old World Plane Tree 

 (Platanus orientalis L.) is very commonly planted as a shade tree in the eastern states. 



FORM Usually attains a height of 70-125 ft., but may reach a height of 140-170 ft. with 

 a diameter of 10-11 feet. It is the most massive of the deciduous trees of North America. 

 Trunk usually branches near the base into heavy sub-trunks, vvhich sub-divide and form a very 

 deep, wide-spreading, rather open, and irregular crown. 



BARK On old trunks rather thick, rigid, roughened by shallow fissures separating broad 

 ridges which peel off into thin dark brown scales. On young trunks and upper parts of old ones 

 it peels off spontaneously into large thin plates exposing a whitish, yellowish, or a greenish 

 inner bark. This mottled inner bark is characteristic, but rarely found near the ground. 

 See Fig. 57. 



TWIGS Rather stout, zigzag, at first green and pubescent, later brownish to gray and 

 smooth, decurrently ridged, enlarged at the nodes, marked by numerous, small, pale lenticels, 

 encircled by stipule-scars. Pith wide and white. 



BUDS Alternate; terminal bud absent; sub-petiolar, surrounded by base of leaf -stalk or leaf- 

 scars, i-J of an inch long, conical, dull-pointed, very divergent from section of branch above 

 end slightly from section below, covered with 3 scales, the outer one of which is smooth, 

 shining, reddish-brown, the middle green and gummy, and the inner pubescent. 



LEAVES Alternate, simple, broadly ovate, 3-5-lobed, toothed on margin, 4-10 inches across, 

 bright green above, pale green and white woolly below. Petioles about 2 inches long, round, 

 with enlarged hollow bases. Stipules 1J inches long, conspicuous, encircling twig. 



LEAF-SCARS Alternate, 2-ranked, unequal in width, have a wavy outer margin, nearly 

 encircle the buds at enlarged nodes of branches, fcrm an angle of about 60 degrees with the 

 section of branch below, contain 5-10 bundle-scars which are arranged in a curved line and 

 occur singly or in groups. 



FLOWERS Appear in dense heads with the leaves in May. Staminate and pistillate flower 

 heads occur on different stalks. Staminate are axillary and dark red; pistillate terminal, 

 greenish and often tinged with red. 



FRUIT Matures in October. Occurs solitary or rarely in 2s in brown heads about 1 inch 

 in diameter suspended from a slender stalk. Heads often persist far into winter and are 

 composed of many hairy achenes about I of an inch long. 



WOOD Diffuse-porous; rays conspicuously broad; pores minute; hard, difficult to split, 

 reddish-browr with light to jyellowish sapwood. Weighs 35.39 Ibs. per cubic foot. Used in the 

 manufacture of furniture, interior furnishing, crates, tobacco boxes, and charcoal. 



DISTINGUISHING CHARACTERISTICS The Buttonwood, also known as Buttonball, Syca- 

 more, and Plane Tree, can readily be distinguished in summer by its massive form, its 

 whitish, yellowish, or greenish bark of the upper branches which at times are covered with 

 large, thin, dark brown scales of outer bark. The large leaves with their enlarged hollow- 

 based petioles and the flowers in the form of neads, are also characteristic. In winter the 

 massive form and whitewashed appearance of the upper branches is distinctive. The smooth, 

 reddish, sub-petiolar buds covered by a single exposed scale and surrounded by a leaf-scar 

 with 5-10 bundle-scars will prevent one from confusing it with any other of our native species. 

 The persistent fruit which usually occurs solitary is readily distinguished from the oriental 

 species which bears its fruit in clusters of 2-4. 



RANGE Maine and Ontario south to Florida, Avest to Minnesota, Nebraska and Texas. 



DISTRIBUTION IN PENNSYLVANIA Common along streams, especially in the eastern, 

 southern, western and central parts of the State. 



HABITAT Prefers racist, fertile soil, but will grow in rather dry soil. Best development In 

 the moist valleys of the Ohio and Mississippi rivers. 



IMPORTANCE OF THE SPECIES The wood of this species is annually becoming of more 

 commercial importance and hence it should be planted at least to a limited extent. It may 

 be grown from cuttings or from seed. It is planted sparingly for ornamental purposes but 

 the Oriental Sycamore seems to be preferred eince it is more attractive and less subject to 

 fungous diseases. 



