Structure and Function of Endodermis in Abietinece 279 
tion of these walls; communication between adjacent endodermal 
cells is afforded by means of the simple unthickened pits present in 
the radial walls. 
Fig. 6. Pinus sylvestris L. Part of a transverse section from*the base of a 
needle showing the developing endodermis and pericycle. en., endodermis; 
per., pericycle; scl., sclerenchyma. ( x 240.) 
II. Pinus laricio Poir. 
The leaves of the Corsican Pine have an endodermis resembling 
very closely that of Pinus sylvestris. The endodermal layer appears 
very regular in transverse section. The radial walls are suberised and 
pitted, the suberin layer, as in Pinus sylvestris, being deposited on 
the outside of a central core of lignified material. The inner tangential 
walls are pitted and consist mainly of lignocellulose with some un¬ 
thickened cellulose portions. The outer tangential walls are of ligno¬ 
cellulose with patches of suberin on the inner side. The transverse 
walls resemble in structure the radial walls, but are unpitted. With 
the exception of the unlignified portions of the inner tangential walls 
