326 



PLANT J.ll-F. 



upper to the lower side of the leaf may act as reservoirs 



of water. 



442. 3. Tubers and bulbs. — These forms of the shoot 

 in which the parenchyma is 

 abundant and richly supplied 

 with water may also be 

 counted, in part at least, as an 

 adaptation for water-storage. 

 443. III. Halophytes. — 

 The salt-loving plants arc, 

 in most of their characters, 

 strikingly similar to the xero- 

 phytes. This similarity is to 

 be explained probably by the 

 difficulty of securing a suita- 

 ble water supply. They grow 

 near the ocean, upon the 

 shores of salt lakes, by salt 

 springs, and in the interior 

 of the great continents in old 

 lake basins in which the salts 

 have accumulated by the 

 rains. A few of the halophytes 

 are trees and shrubs, with 

 leathery leaves, but almost all 

 are succulents. In habit thev 



Fig 370. — Strip from a vertical section of 

 leal "I Peperomia trichocarpa. ./, from 

 afreshleaf; w, water-storing tissue, com- ov»n*»rallv In™ nft*»n ,-.-,.,> 1, 



posed of the multiple epidermis of the arC ,^lUiall\ IOW, otUll ( Ucp- 



upper side ;*, chlorophyll-bearing cells; • j, ( jj , fl « ■,,,(! 



s, spongy parenchyma with sparse chloro- " J 6» " ll " nnii\, iksiij aiiu 



plastS and much water. /.'. tin- same after ____, _, 1 , . #.___ ,1,, . ,„ f 1 ^„,. c . 



four days" tr.mspirati,,,, at ,s ,.. C. The nl(>r « <" lesstiailsllH Cllt lea\ CS 



tissue w is much collapsed, the walls being „_ i , __. . 4 i, ii i__ ,, i 



|,l..it.-,i : .also shrunken, but « as before, and stems; the cells large and 



S ified about 5 ° diam - Vfl - Haber - thin-walled, containing com- 

 paratively little chlorophyll and abundantly supplied with 

 water, with few and small intercellular spaces and the surface 

 generally smooth. 



