PLATANUS 201 



which are sometimes solitary, but more often strung two to six together 

 on a pendulous stalk. They persist on the tree more or less throughout 

 the winter. The bark peels off in large flakes, and after a stormy spring- 

 day the ground beneath a large plane will frequently be seen strewn with 

 pieces of bark torn off by wind. 



Some of the noblest trees of the northern hemisphere belong to this 

 genus. Specimens of the European P. orientalis are known to have 

 trunks 40 ft. in circumference, and -the American P. occidentalis growing 

 in the Mississippi Valley has trunks about as large, and it occasionally 

 reaches 170 ft. in height. They like a deep, moist, loamy soil, and thrive 

 better in the south of England than in the north. They are essentially 

 sun-lovers. Seeds ripen on P. acerifolia and orientalis, and germinate 

 readily. Young plants may also be obtained from cuttings, which should 

 be made at the fall of the leaf, of shoots 8 to 12 ins. long, with a "heel" 

 of old wood at the base, and placed under a handlight in a sheltered spot. 

 In nurseries they are usually propagated from stools by layers. Young 

 plants are rather subject to being cut back by frost. 



The plane trees of town streets and promenades are under suspicion 

 of causing serious bronchial irritation by shedding the hairs from their 

 leaves, and especially fruits. These break up into minute particles which, 

 floating in the air, are inhaled. Although the alleged evil influences of 

 these particles on the throat and lungs (and even on the eyes and ears as 

 well) were suspected and written about by the ancients among others by 

 Galen and Dioscorides they never appear to have deterred either them 

 or later generations from planting the tree freely. There seems to be 

 little doubt that on the Continent it produces, or helps to produce, a 

 catarrhal affection analogous to hay fever. In Britain the crops of fruit 

 are not so large, and probably our damper climate prevents the hairs 

 travelling far from the tree ; at anyrate, nothing has been proved against 

 the tree to justify its wholesale condemnation. 



P. ACERIFOLIA, Willdenow. LONDON PLANE. 



A deciduous tree of the largest size, frequently over 100 ft. high, with a 

 smooth, erect trunk, whose park peels off in flakes, and a huge, rounded head 

 of branches, the terminal parts of which in large trees are pendulous ; young 

 shoots and leaves covered at first with a dense, pale brown wool much of which 

 falls away by autumn. Leaves 5 to 10 ins. wide, usually rather less in length ; 

 five-lobed, the lobes triangular and extending from one-third to one-half the 

 depth of the blade, more or less coarsely toothed ; stalk i to 4 ins. long. 

 Fruit-balls two to as many as six in a pendulous string, each I to i ins. 

 across, rendered burr-like by the long, persistent remnant of the style at the 

 apex of each fruit. 



The origin of this plane is not known. Like the red horse-chestnut, it 

 has never been found wild, and all the old historical planes of the Orient 

 ar'e P. orientalis. Now the commonest of planes, it first came into notice 

 early in the eighteenth century. In London it is planted in greater numbers 

 than all the other sorts of trees put together. It certainly has the power to 

 withstand a smoke-laden city atmosphere better than any other tree at 

 present known. Years ago some ingenious person suggested that this faculty 

 was due to its habit of casting its bark, and this theory has been religiously 

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