36 



surrounding the plants given as typical illustrations, such 

 as Helichrysum, Salvia &c, notwithstanding they are in 

 most respects the exact opposite of those surrounding 

 the ferns, we may yet find a certain parallel which 

 suggests a similar reason for the presence of the raised 

 stomata. 



Our first example, Helichrysum petiolatum originates 

 from the Cape of Good Hope : According to the accounts 

 of Botanists, who have travelled in this region for the 

 purpose of studying the Flora, both soil and climate 

 work together to retard the growth of vegetation. The 

 soil along the coast is so sandy and shallow that it has 

 very little power to hold the water falling as rain, while 

 in the interior the sand is mixed with clay ancl baked 

 so hard by the sun as to render it almost of the consis - 

 tency of bricks. The amount of rain falling through 

 the year is small, and what is still more disadvantageous 

 for vegetation, of very irregular occurence. Notwith- 

 standing these disadvantages of outward circumstances, 

 a great variety of vegetable forms exists and flourishes 

 here. As might be expected, one finds every possible 

 device which nature makes use of to defend itself against 

 these untoward outward conditions. The predominating 

 shrubs belong to the Ericaceae or Proteaceae*), the trees 

 are largely those whose leaf organs are reduced in surface 

 as much as possible, often furnished with thorns of extra- 

 ordinary size. Succulent plants abound, also Halophyten 

 and resin bearing plants. Among other means for resisting 

 drouth may be reckoned the hairy coating of the leaves 

 of such herbs as Gnaphalium and Helichrysum. The 



Grisebach, Veg. cler Erde. Bd. II, P. 187. 



