THE PLANE TREE FAMILY 



PLATANACE^ Lindley 



HIS family of one genus with about 7 species, are trees of the north 

 temperate zone. They are tall trees, with large, broad leaves and 

 thin, light-colored, exfoliating bark. Several fossil forms, also, are 

 known from the Cretaceous and Tertiary periods, being found as 

 far north as Greenland. 



The leaves are simple, alternate, palmately lobed, prominently veined, with 

 long petioles, the hollow base of which encloses the bud for the following season; 

 the stipules are large, entire or toothed. The flowers are monoecious, small and 

 closely inserted on a globose, more or less fleshy receptacle, forming long-stalked 

 heads, which are soUtary, in spikes, or racemes; the perianth is very small, con- 

 sisting of 3 to 6 outwardly hairy sepals and an equal number of thin, smooth petals; 

 the staminate flowers are in axillary reddish heads; the stamens are as many as 

 the sepals and opposite them; the filaments are very short, the anthers elongated; 

 the pistillate heads are terminal and green, consisting of an equal number of small 

 sepals and petals, with 2 to 8 distinct i -celled carpels, mingled with rudimentary 

 stamens (staminodes), and surrounded by persistent, long- jointed hairs; the style 

 is terminal, and stigmatic for about half its length; the ovary is solitary, rarely 

 2, linear and i-celled. The fruit is a globose, compact head, composed of many 

 elongated inverted pyramidal nutlets, surrounded by stiff, erect hairs; the seed is 

 pendulous, elongated, has fleshy endosperm, and a straight, linear embryo. 



The name adopted by Liimseus for these trees is the Greek classic name of the 

 European plane tree, Platanus orientalis Linnaeus, the type of the genus. The 

 common name Sycamore, most used for these trees in America, properly belongs 

 to the Old World tree Ficus Sycamorus Linnaeus, of the Fig family. 



THE PLANE TREES 



GENUS PLATANUS [TOURNEFORT] LINN^US. 



Fruit heads solitary, rarely two together; eastern tree. ' 1. P. occidenUMs. 

 Fruit heads racemose. 



Lateral heads usually stalked; leaf-lobes elongated; southwestern tree. 2. P. Wrightii. 



Lateral heads usually sessile; leaf-lobes relatively short; California tree. 3. P. racemosa. 



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