384 MR. T. W. WOODHEAD ON THE 
leaf differs from the heath-form in that the epidermis has rather 
thicker walls, the stereom beneath is discontinuous, the fibres 
are smaller with a tendency to form chiefly under the lateral 
epidermal walls, being continuous only at the angles. Similarly, 
the walls of the mesophyll and endodermis are thinner. 
When growing in moist situations in the deep shade of Elm 
and Beech, as it frequently does on the wooded hill-slopes, its 
Figs. 44-47. 
Leaves of Deschampsia flexuosa from plants growing under different conditions. 
Fig. 44. Diagram of Transverse Section. 
45, Portion of Trans. Sect, Sun-form. 
46. Portion of Trans. Sect. Oak-wood form. 
47. Portion of Trans. Sect. Under shade of Ulmus and Fagus. 
leaves are more slender, limp, and all tend to droop in one 
direction. In transverse section (fig. 47) the epidermal cells are 
seen to be smaller, with a thin cuticle, the stereom is dis- 
continuous, the fibres are only slightly thickened, and the cells 
of the mesophyll are thin-walled. In the endodermis a cell 
