48 PLANT STUDIES 
small plants growing in exposed situations, as bare rocks 
and sandy ground. The cluster of leaves, flat upon the 
ground, or nearly so, and more or less overlapping, is very 
effectively arranged for resisting intense light or drought 
or cold (see Figs. 11, 12, 48). 
38. Protective positions. In other cases, a position is 
assumed by the leaves which directs their flat 
surfaces so that they are not exposed to the 
most intense rays of light. The so-called 
FIG. 41. A leaf of a sensitive plant in two conditions. In the figure to the left the 
leaf is fully expanded, with its four main divisions and numerous leaflets well 
spread. In the figure to the right is shown the same leaf after it has been 
"shocked" by a sudden touch, or by sudden heat, or in some other way. The 
leaflets have been thrown together forward and upward ; the four main divisions 
have been moved together ; and the main leaf-stalk has been directed sharply 
downward. The whole change has very much reduced the surface of exposure. 
After DUCHARTRE. 
pass plants," already mentioned, are illustrations of this, 
the leaves standing edgewise and receiving on their surface 
the less intense rays of light (see Figs. 5, 170). In the 
dry regions of Australia the leaves on many of the forest 
trees and shrubs have this characteristic edgewise position, 
known as the profile position, giving to the foliage a very 
curious appearance. 
Some leaves have the power of shifting their position 
according to their needs, directing their flat surfaces to- 
ward the light, or more or less inclining them, according 
