p o 5 t e i 5 i a 63 



foliar structures, and even when 

 epigean, as Gcebel notes, they usually 

 differ in a marked degree from the 

 ordinary foliage leaves. If similiar in 

 outline, there is almost always a decided 

 difference in venation. These variations 

 have been explained as a retention of 

 the form of ancestral leaves by the 

 cotyledons. Were this true one should 

 expect to find similar cotyledons 

 throughout a family, or at least among 

 the species of a genus. 



The habitual production of three 

 cotyledons of equal rank by Nuytsia 

 floribunda would, according to the foliar 

 theory, indicate that it represents a 

 third class of Angiosperms (Tricotyle- 

 dons) in which three leaves instead of 

 two or one were originally arrested in 

 the seed. But, as a matter of fact, 

 numerous dicotyledons occasionally pro- 

 duce embryos with three and sometimes 



