Hknky and Flood — Thr Ilisfriri/ of thr Lnnihni I'lunr. 17 



leaved form exists in Cyprus, possibly a peculiar geographical variety. Culti- 

 vated trees in England show an apparent great diversity in the furni of the 

 leaf ; but the range of variation is ehietiy confined to the width of the lobes 

 and the dentation of the margin. 



No attempt is made in this paper to deal with the possible varieties of 

 this species in the wild state, for which a study in the field is requisite. 



The Oriental Plane, which is not readily pi'opagated from cuttings, is never 

 used for planting in streets in Europe or North America. It is much less 

 hardy on the Continent than the London Plane. 



2. Platanus occidentalis, L. Occidental Plane. 

 Plate V, fig. 2. 



A very large tree, variable in the size and shape of the leaves, which in 

 some cases are 5-6 inches across, in others 8-10 inches wide ; either obscurely 

 or plainly 3-lobed ; lobes short and triangular, the sinuses separating them 

 not reaching one-third the length of the blade ; base cordate, rarely showing 

 a central cuneate part; main nerves three, normally arising at the junction of 

 the petiole with the blade ; margin rarely entire, usually with few or many, 

 small or large sinuate teeth ; tonientuni persistent on the nerves and petiole. 

 Fruit-balls solitary at the end of the peduncle, smooth, large, averaging 1^-1| 

 inches in diameter ; composed of closely packed achenes, and not showing any 

 hairs between them. Achene with a glabrous flattened head, bearing in a pit 

 on its summit the remains of the style, which breaks off early ; body elongated, 

 glabrous except for the ring of long hairs at the base and the narrow tomen- 

 tose ring at its junction with the head. 



P. occidentalis is the most massive and tallest deciduous tree of the great 

 forests of the eastern half of the United States, where it usually grows on 

 alluvial soil. It is an extremely rare tree in cultivation in Europe, and is 

 difficult to keep alive, as it puffers much when young from the continued effect, 

 year after year, of spring frosts on its tender shoots. It is easily raised from 

 seed, and is said to be readily propagated by cuttings. It is unsuccessful as a 

 street tree in the towns of the United States. The Superintendent of Parks 

 Washington, says that young trees of this species are very promising in streets 

 for ten or fifteen years, when they almost invariably begin to die. The cause 

 of death is obscure, but is generally attributed to the attacks f>f a minute 

 fungus, Glocosporiam verviscqvium, which kills the young leaves in May or 

 June, though a second crop of leaves clothes the branches in .Inly. Platanvs 

 accrifolitt is less subject to this disease. Whatever be the explanation, it is 

 very remarkable that this magnificent forest tree is qiiite unsuitable for street 

 planting in its own country, where the London Plane is so useful for this 



B.I. A. PROC, VOL. -KXXV, SKCT. B, [C] 



