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Transactions. 



have their walls suberized. The cortex consists of cells in which the 

 cell-walls, composed of cellulose, are very much thickened ; the tissue is 

 compact, with only small intercellular air-spaces. The cortical cells vary 

 considerably in size : in the outer part of the cortex they are large, and 

 irregular in shape ; in the inner part they are much smaller, and more or 

 less oval in section. A large amount of starch is stored up in the cortex. 



The endodermis and the pericycle are not clearly defined. The xylera 

 occupies the whole of the centre of the root, and is surrounded by a con- 

 tinuous zone of phloem. The vessels of the xylem are scattered ; they are 

 of large diameter and have thick walls. Accompanying the vessels there 

 is a large amount of xylem parenchyma which consists of rectangular or 



irregular thick- walled cells. 



« 



3. Plantago triandra Berggr. 



This plant is illustrated in fig. 18. It is a small plant, with a short, thick 

 rootstock bearing numerous radical leaves. These leaves are |— 2 in. long, 

 with irregularly and remotely serrate margins, and sparingly pilose on the 



Fig. 18. — Plantago triandra. Entire jilant (natural size). 



upper surface with short hairs, the lower surface being glabrous. The root- 

 system is short, and consists of a mass of fibrous roots which do not branch 

 very much. 



Anatomy. 



Leaf (figs. 19-22). — The upper epideimis is sparingly pilose, the hairs 

 being long, jointed ones, consisting of about 6 cells (fig. 21). The basal cell 

 is very large and is more or less circular ; its diameter is 2-4 times that of 

 the other epidermal cells. This basal cell is thin- walled at the bottom, 

 but at the outside the wall is much thickened. The rest of the cells of the 



