Leaf size of plants can be described using the terms megaphyll, macrophyll, mesophyll, microphyll, nanophyll and leptophyll (in descending order) in a classification devised in 1934 by Christen C. Raunkiær and since modified by others.
[2] Some authors simplified the system to make it specific to particular climates,[3] and have introduced extra terms including notophyll,[3] picophyll,[4] platyphyll[4] and subleptophyll.
[6][7] Christen C. Raunkiaer proposed using leaf size as a relatively easy measurement that could be used to compare the adaptation of a plant community to dryness.
We have for a long time been aware of a series of different adaptations in the structure of plants enabling them to endure excessive evaporation, and thus allowing them to live in place where the environment determines intense evaporation, or where the conditions of water absorption of the ground are unfavourable either physically or physiologically.
Examples of such structures are: (1) covering of wax, (2) thick cuticle, (3) sub-epidermal protective tissue, (4) water tissue, (5) covering of hairs (6) covering of the stomata, (7) sinking of the stomata, (8) inclusion of the stomata in a space protected from air currents, (9) diminution of the evaporating surface, &c. The matter however is so complicated that it is very difficult to reach an exact appraisal of these adaptations in characterizing the individual plant communities biologically.