RELATION OF LEAF STRUCTURE TO PHYSICAL FACTORS 47 



enchym (155/1) I row globose cells 30 /A, lining the epidermis and 

 joined at intervals across the leaf by similar cells with air-passages 

 between. (Plate I, fig. 40.) 



AERIAL : light I ; humidity 80-90% : staurophyll 450 /* ; epi- 

 dermis 15 ju,; chlorenchym (420/4) chains of prolate cells SO/A, 

 traversing the leaf, close in the palisade area except for the stomatal 

 air chambers, loose and more irregular in the sponge region. 

 (Plate I, fig. 46.) 



Submerged C. 155 M P. OM S. 155 /* 



Aerial C. 4201*. P. 420 M S. OM 



+ 265/4 +420/* 155 M 



Light -f; water and temperature the same; humidity (10- 



20%). 



AMPHIBIOUS (dwarf) : light I ; available water 58% ; humidity 

 50-70% : similar to the aerial leaf in structure although the plant 

 is exceedingly dwarfed. 



Light -}-; water 42%; temperature the same; humidity 

 (30-50%). 



Sparganium angustifolium 



FLOATING: light i ; available water 100% ; humidity 100% ;* tem- 

 perature 4O-65 : diphotophyll, lenticular in cross section; 600 /* 

 in center, 200 /* towards edges; epidermis 15/1; cuticle thin; chlor- 

 enchym (570/1) 3-4 compact rows prolate palisade cells 30/1; I 

 row globose and oblong sponge cells 15/4; 3 air-passages each 

 side of midrib, crossed frequently by diaphragms of 5-6 lobed star- 

 shaped cells, and separated from each other by partitions of paren- 

 chyma cells containing bundles. (Plate I, fig. 50.) 



AMPHIBIOUS (dwarf) : light i ; available water 58% ; humidity 

 50-70% : plant greatly dwarfed but no change in leaf structure. 



SUBMERGED: light : leaf 500/1; epidermis 35/1; chlorenchym 

 (430/1) a one-celled layer of oblate cells next to the epidermis 15/4; 

 diaphragm cells 6-7 lobed elongated horizontally. (Plate I, 

 %5&0 



Floating C. 570 /* P. 3-4 rows, 120 A* 8.15** 



Submerged C. 430 M P. i row, 15 A S. 15 M 



140/1* (2-3) rows, IDS/* (97%) o 



Floating Air spaces, 435 M 



Submerged Air spaces, 400 M 



