A^ND THE DISTEIBUTION OF THE STOMATA. 



107 



Group 4. — More stomata on the upper surface than on tlae 

 lower : stomatal formula greater than j. 9 species. 



Acacia decipiens —4 Vertical. 



Achillea Millefolium ^^ 



Alisma Plantago — -^ 



Araucaria imbricata -_ 



Ranunculus Flammula — Some leaves have bloom abova. 



Sedum acre - Succulent, 



4 



S. album — Succulent. 



107 



Sempervivum tectorum — Succulent. 



75 



Statice incana :r: 



Among the above 148 plants are some which cannot fairly be 

 compared with the rest, from their different structure. These 



are : — c,. ^ 



btomata. 



. . , . . 103 



Acacia decipiena r^ 



Rhipsalis crispata j2 



Sedum acre ; -g 



S. album ". j 



Sempervivum tectorum 7 



r 



Yucca aloifolia ^ 



Acacia is excluded because of the vertical position of its leaves. 

 The succulents are obviously not comparable with ordinary leaves 

 in the matter of stomata di.^tribution. In a thick fleshy leaf, with 

 relatively few stomata, the few that do exist may be necessarily 

 more evenly distributed than in a thin leaf. 



If we divide the species into two sets — (A) in which the 

 stomata on the upper surface are one third or less than one third 

 of the whole number of stomata ; (B) where they are more than 

 one third of the whole — we have : — 



104 out of 137 species, or 76 per cent., in Class A. 

 34 out of 137 species, or 24 per cent., in Class B. 



