1920.] 



Scorching ok Foliage. 



481 



localities far inland, examples beinpf found i^ccording to 

 Warming* in oak-scrub in Central Jutland or in the centre of 

 Switzerland." Statements of this kind, of course, leave some 

 doubt as to the precise nature of the injuries which have ulti- 

 mately led to the one-sided growth. There are, however, data 

 which show that damage to leaves by wind in the absence of salt 

 can be quite similar to that effected by sea-winds. An instance 

 is given by a record of the scorching of leaves of tre^-^s and shrul)s 

 by a wind at Burlington, Vermont, U.S.A., in July. 1900.1 The 

 wind was described as unusually heavy and dry, {)nd, being from 

 the west, there was no question of the effect being due to salt. 

 Leaves were killed on the west side of the trees, especially the 

 outer trees along the western margin of the woodlands, and 

 also on the same side of different shrubs, the scorching usually 

 beginning at the apex and margin of the leaf. 



Hansen, t who made observations on the East Friesian Islands, 

 discusses the question of the cause of the injuries to leaves, 

 noticed by him, at considerable length, and concludes that wind' 

 is the all-important factor responsible for the damage. The ex- 

 planation of the phenomenon given by him§ and other writers 

 is that, owing to the drying action of the wind, water is so r-uickly 

 removed by evaporation from small portions of leaf-tissue that 

 there is no time for conduction of water from the neighbouring 

 cells, and that the tissue concerned consequently dries up and 

 becomes brown. Hansen observed that the drying of the leaves 

 began at the apex and margin, and that leaves were often 

 completely killed, not by gales, but by long-continued vinds of 

 ordinary strength, the process of drying being a slow one, and 

 progressing gradually from the margin inwards. The same type 

 of withering, beginning at the apex and margin. || may often be 

 seen, as a result of exposure to strong winds, in different inland 

 localities (away from exposure to salt), and is indeed a common 

 effect of prolonged insufficiency of water in the leaves cf trees, 

 shrubs and herbs, 11 and may also be brought about experimen- 



* Warming. Oerology of PI ant a, Eng. ed., 1909., p. 37. 



t VMh Ann. Rrpt., Vprmont Agric. E.rp. Sta., 1900. pub. 1901. pp. 2S1-2. 



+ Ilaiisen. Die Vegetation der Ostfnesischen Instcln, Darmstadt. 1901. This 

 work contains numerous references to literature and much criticism. Kroll. 

 Windund Pflanzenwclt. Beih. Bot. Centralbl., Vol. :^it (1918). 1. p. 125. 



§ Hansen, loc. cit., p. .32. 



II Then sometimes in patches between the larger veins, the parts first afifected 

 being those to which water can be less rapidly supplied. 



^ Yapp, Spiraea Uhnaria, L. and its Rcarini: on the Problem of Xeromorphv 

 in Marsh Plants, Ann. Hot., Vol. 2(\ , p.S15 (1912) : Hansen. Flora.\o\. 93, p. 32 

 (1904). See also SchriMler. I'eher den Verlanf des Welketi*, Diss. Gottingen. 1909,. 

 ref. Bot.Centralbl.. V..!. 111. p. 3.-3 (1910). 



