i9"J STARR— ANATOMY OF DUNE PLANTS 



295 



Swamp forms 



Sometimes a moving 



and the members by increased length of stem keep pace with it 

 for a time; a few of these have been examined and compared with 

 forms growing in their natural habitat. 



Leaf 



PLATANUS OCCIDENTALS 



Stem 



s X s X 



T IS2 a (136-162) 199 /* (162-205) N 66 69 



UE. . . 23 =15 per cent 25 = 12 per cent D 35 p (50) 46 m (63) 



P 52 =34 63 =32 W.... 3.2 3.2 



Sp.... 62 =41 g2 = 4 6 p 5 3.2 



LE... 16 =10 19 =10 L 6.4 7 



0W — * 2.8 R.... 3 2 



C 68 6.9 



S 100 116 



Collen 56 109 



The dune form has thicker leaves than The dune form shows an increase in 



the swamp form, but the palisade and number and size of the vessels, but there 

 outer wall of the epidermis are excep- is no increase in woody tissue furnished 

 tlonaL by the fibers. There seems to be no 



diminution in growth as indicated by 

 the growth rings, but mechanical tissue 

 outside the stele and the cork have in- 

 creased. 



us INCANA 



N, 

 D 

 W 

 F. 



L. 



Stem 



5 x 



68 61 Swamp form, vessels larger than the 



29 34 others but fewer in number. Dune 



2.5 2.6 form, larger area of vessels. Thickness 



3.5 3.4 of walls about the same. 



7 8.8 



CEPHALANTHUS OCCIDENTALIS 



Leaf 

 5 X 



•• • I 7S M (143-168) 163 /x (147-189) A second layer of palisade is partly 



16 = 9 per cent 17 =10 per cent organized in the swamp form and com- 



*••• 54 =31 48 =29 pletely in the dune form. The first 



p.. 91 = 5 2 84 =52 palisade is relatively shorter in the dune 



• x 4 = 8 I4 = g form, but the second is so much more 



3 3.7 compact than in the swamp form that it 



u - I -6 2 must more than make up the amount 



of tissue. In both forms stomata are 

 found on the lower surface only and the 

 side walls of the epidermal cells are 

 waxy. 



