The Effect of Smoke on Plant Life
Journal of the Royal Sanitary Institute
FR( )~i experience in working as landscape-gardener to the 3ietrop<>litaii F Puhlic Gar(l(-iis' Association I have been askecl to say something about the effect, of smoke on vegetation. oot is the chicf enemy to vegetation. The nnety divided particles of carbon which constitute soot. settle in masses as smuts, or drift about, Invisibly small, and become evident as a deposit. They penetrate into the pores of plants and interfere with all fuucti&dquo))-~ of the leaves: with translliratioll of
... nslliratioll of water-vapour, and with Inspiration of air. Unless transpiration is freely allowed the sap can circulate but sluggishly. Unable to get rid of water no more can enter, and the passage of fuod-materials from the root is (-Iiecke(I ; and unless air, with its supplies of oxygen and of carbon dioxi<1e~ can enter, the plant suffers starvation in that direction also. Indeed, were it not that a 1)l:~nt's stomutu are almost entirely on the under sides of the leaves, no plant could survive a London fog. Everyone lias noticed how ouickly tile colour of pant deepens in town. The emerald-green uf newly painted Westminster Bridge in a few weeks is a sober, olive hue. Consider what. a deposit that so darkens colour must he to a 1)lant which depends on light for all its chemical processes. Every dirty plant is living practically in twilight. About once a week, during the winter months, the plants In the little garden of the Bank of England, are 7emul washed, as one washes room-plants, with soap '.ind water, otherwise they would hardly appear green. After a spell of foggy weather I have seen the leaves iridescent with a tarry film, so greasy is the soot. Of course, hand-washing is out of the question in large spaces, and one has to fight this evil of dirt by planting only such things as have shinv or smooth leaves, on wlli.cll soot cannot get too firm a hold for rain to partially dislodge it. Even so they are but sickly specimens, and in all cases the lower leaves tend to drop off prematurely, owing to their receiving a dotible portion of dirt in drips from ahoB&dquol'. Lumluu shruhs rarely '*break&dquo from below: the stems are too coated for young life to get through.