372 



TREES OF NORTH AMERICA 



of the leaves and the amount of pubescence on their lower surface, in the pointed or obtuse 

 apex of the akene, and in the number of heads of pistillate flowers on their peduncle. 



Of the exotic species, the Old World Platanus acerifolia Willd., of doubtful origin, and 

 often considered a hybrid between P. orientalis L. and the Plane-tree of the eastern United 

 States, is now a common street tree in the cities of all the countries of temperate Europe, 

 and is largely used as a street and shade tree in the eastern states and in California. 



Platanus is the classical name of the Plane-tree. 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Heads of fruit usually solitary; leaves broadly ovate, slightly 3-5-lobed, the lobes broad, 

 mostly serrulate, or entire, truncate or rarely cuneate at base. 1 . P. occidentalis (A, C) . 

 Heads of fruit racemose. 



Leaves 3-5-lobed to below the middle, the lobes entire, remotely and obscurely dentate, 

 or rarely sinuate-toothed, truncate or slightly cordate or cuneate at base. 



2. P. racemosa (G). 



Leaves deeply 5-7-lobed, the lobes elongated, slender, entire, or rarely remotely dentate, 

 deeply cordate or rarely cuneate or truncate at base. 3. P. Wrightii (H). 



1. Platanus occidentalis L. Sycamore. Buttonwood. 



Leaves broadly ovate, more or less 3-5-lobed by broad shallow sinuses rounded at the 

 bottom, the lobes broad, acuminate, sinuate- toothed w r ith long straight or curved remote 

 acuminate teeth, or entire with undulate margins, truncate or slightly cordate, or long- 



Fig. 331 



cuneate and decurrent on the petiole at base (var. attenuata Sarg.), thin and firm, bright 

 green on the upper surface, paler on the low r er, glabrous at maturity with the exception 

 of a slight pubescence on the under side of the thin midrib and stout yellow veins, 4'-7' 

 long and broad, or twice as large on vigorous shoots and then frequently furnished with 

 dentate basal lobes; petioles stout, terete or slightly angled, becoming puberulous 3'-5' in 

 length;' stipules I'-li' long, entire or sinuate-toothed. Flowers : peduncles coated with pale 

 tomentum, bearing 1 and sometimes 2 heads of flowers. Fruit: heads 1' in diameter, on 

 slender glabrous stems 3'-6' in length; akene about f ' long and truncate or obtusely rounded 

 at apex. 



A tree, occasionally 140-170 high, with a trunk sometimes 10-11 in diameter above 

 its abruptly enlarged base, often divided near the ground into several large secondary 

 trunks, or rising 70-80, with a straight column-like shaft free of branches and with little 



