Leaves by the Acre
Probably no one ever had time and patience, or thought it worth while, to measure the leaf surface exposed by the total foliage of a large tree. But one may readily enough measure a few leaves, and make an estimate; and it then appears that the leaf surface of a good sized tree must be measured in acres. When we reflect that the breathing pores are scattered thickly over the under surfaces, and sometimes over the upper surfaces also, of the leaves, and reflect that under normal circumstances each pore is taking in air and giving out moisture, it no longer seems surprising that a tree must send its roots far into the earth in search of water, or that the carbon taken from the air can build up as rapidly as it is observed to do the bulk of the tree trunk. A few leaves spread out together, as in the picture, give one a realizing sense of the way in which the surfaces take up space. Remember, too, that each leaf has a lower surface, doubling the area here exposed.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 7 Chapter 1