Structure and Function of Endodermis in Abietinece 285 
rarely lignified, some having very thick cellulose walls, especially 
cells found towards the abaxial side of the leaf. 
The xeromorphy of the leaf is, as might be expected for a 
deciduous tree, less marked than that of the leaves previously 
described. The suberisation of the radial and transverse walls follows 
the plan found in the other species investigated with the exception of 
a few passage cells. 
Fig. 10. Abies pectinata D.C. Transverse section through the base of the leaf 
showing the incomplete endodermis. en., endodermis; cut., cuticle. 
( X240.) 
VIII. Abies pectinata'D.C. 
A certain amount of dorsiventrality can be observed in the leaves 
of the silver fir, palisade tissue occurring towards the upper surface, 
and lacunar tissue towards the lower surface of the leaf. 
The endodermis resembles that of Picea excelsa in its irregularity 
at the base of the leaf (Fig. 10). As in Picea the lack of continuity 
in the endodermal sheath is accompanied by the greater elaboration 
of lignified hypodermal tissue in this region, three or four rows of 
