PLATANACEAE 



American Sycamore. Planetree 

 Platanus occidentalis L. 



HABIT. A large tree 70-100 feet high and 3-8 feet in diameter 

 (max. 175 by 14 feet); with yellow-poplar the largest of eastern 

 hardwoods; long, clear bole; open crown. 



LEAVES. Alternate; simple; deciduous; broadly ovate; 3-5 

 lobed; 4-7 inches long; lobe margins coarsely toothed; thin 

 and firm; bright green and smooth above, paler and hairy along 

 the veins below; petiles 2-3 inches long. 



FLOWERS. Monoecious; both male and female in heads 

 with minute individual flowers, each containing 3-8 sepals and 

 petals; appearing with the leaves. 



FRUIT. A multiple, globose fruit 1-114 inches in diameter; 

 of elongated, obovoid achenes with spur at apex and ring of 

 erect hairs around base; maturing in one year; borne singly 

 on items 3-6 inches long. 



TWIGS. Rather stout; round; orange-brown; lustrous; pith 

 round, homogeneous. Winter buds: terminal absent, lateral 

 V^-y% inch long, conical, brown, with single visible scale, formed 

 within petiole base. 



BARK. Red-brown and scaly near base; thin and character- 

 istically mottled on upper trunk by exfoliating outer layers 

 which expose lighter colored inner layers. 



WOOD. Intermediate in importance; diffuse-porous with 

 broad rays; fairly hard and heavy; heartwood light red-brown; 

 used for boxes, cooperage, vehicles, furniture, ties, and fuel. 



SILVICAL CHARACTERS. Very intolerant; rapid growth; 

 on moist sites; shallow, lateral roots; withstands smoke. 



The following key distinguishes between our 3 native and 



2 widely planted introduced species: 



1. Heads of fruit solitary or in pairs; leaves not deeply lobed. 



2. Leaf lobes broader than long; fruit heads usually single 



P. occidentalis L., American Sycamore 



2. Leaf lobes about as long as broad; 2 (rarely 3) fruit heads per 



stem X P. acerifolia Willd., London Planetree 



1. Heads of fruit usually 3 or more; leaves deeply lobed. 



2. Leaves mostly 5-7 lobed, glabrous to hairy below; Eurasian. . . 



P. orientalis L., Oriental Planetree 



2. Leaves woolly below; native and western. 



3. Arizona and New Mexico; leaves 5-7 lobed 



P. wrightii S. Watts., Arizona Sycamore 



3. California; leaves 3-5 lobed 



P. racemosa Nutt., California Sycamore 



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