84 



another leaf which belonged to the same branch of the above- 

 mentioned plant, but was the oldest one, and the shape of 

 which is approximately cordate. The broadly roundish cor- 

 date form is represented in the leaf in Fig. 119, which leaf 



r 



was succeeded by the regularly heart-shaped one shown in 

 Fig. 120. This, the roundish and more or less cordate form, 

 seems to be the most common one in the young plants, but 

 we might also find the more ovate and sharply pointed form, 

 as, for instance, in the leaves (Figs. ri6-ii8), all of which 

 belonged to the same branch of a very young specimen, 116 



I. 



being the youngest and 118 the oldest one., There is then "*^ 



quite a considerable variation in the foliage in this species, so 

 that forms might occur more or less approaching those of the 

 above-mentioned species, S. glauca d.nd S. hispida. We have 

 accordingly to take refuge in the-^ structure of the leaf, and it 

 seems that some characters are to be found here. The ana- 

 tomical difference must now be looked for in the presence or 

 absence of stomata and in the undulations of the cell-wall of 

 the epidermis. The epidermis of 5. glaitca, taken from the ^ 



superior face of the leaf, does not show stomata, while in the 

 two other species stomata were present and not in small num- 

 bers. The number of the cells surrounding the stomata was 

 nearly constantly two in 5. hispida and four in S, roUmdi- 

 folia. The relative size of the epidermis cells was also some- 

 what different, and, while the undulations were the same in 

 S. glauca and S, rotinidifoUa, the cells of S^ glauca were pro- 

 portionally larger than those of S. rotundifolia. In 5. hispida 

 the cell-walls showed merely a very slight undulation, and 

 the size of the cells was almost the same as in 5. glauca. If 

 we were to examine the epidermis from the inferior surface of 

 the same leaves, we would find stomata present in great num- , 



bers, and equally so in all three species. The undulations of i 



the cell-wall were slighter than those described for the upper 

 surface, especially in 5. hispida, in which the cells show^ed a 

 rectansjular or rhombic form. 



Smilax glauca. 



. A germinating; plantlet of this species, figured on Plate 

 XV, Fig. 123, resembles very much that of S. rotiindifoUa, 



s 



/ 



