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The leaf with the largest surface is most favourable to 

 assimilation, but it gives (all other conditions alike) the 

 largest transpiration too. I have compared the epidermis of 

 the leaves of the parvifoliate types from the dunes with 



Fig. 4 (VJ. 



a: V. arvensis from Koldby Kaas, Samsø (population U, table 1): petals 



parv, leaf lanc-serr, stipules palm, 

 b : Leaf of V. tricolor maritima from Læsø : parvifoliata. 

 c: Leaf of V. tricolor from fields: grandifoliata. 

 The leaves b and c were both from the rosette at the basis of the plant. 



those of the common types and have not been able to detect 

 any difference between them in the number of stomata per 

 unity of area. Therefore, the small leaves on the plants from 

 the dunes must undoubtedly be favourable in reducing the 

 strong transpiration in these places. Just in the dunes we 

 find almost exclusively parvifoliate types. 



Botanisk Tidsskrift. 37. Bind. 24 



