THE LEAF. 



191 



point where, in the normal leaf, the pseudo-stipules are 

 attached. In this series, then, we see every transition 

 between pseudo-stipules and leaf-segments, a fact which 

 most clearly proves that the pseudo-stipules are merely 

 modified leaf-lobes (fig. bla-f) and are not true 

 stipides at all, these being always derived from the 

 leaf-sheath. 



The much-dissected leaves of Planlago Coronopm and 



c ft b 



d e f 



Fig. 51. — Cratsegits sinaica. Foliage-leaves off the same tree, showing 

 transitions (a-f) between pseudo- stipules and leaf -segments. 



the common poppy (Papaver Rhoeas) are occasionally 

 replaced by perfectly entire ones. 



13. Fusion of Cotyledons.* — This is a common pheno- 

 menon in Dicotyledonous seedlings. As a result of it, 

 a single usually forked cotyledon is borne by the seed- 

 ling in a more or less terminal position, the plumular 

 apex being pushed over to one side. Normal cases of 

 the same phenomenon occur in Ranunculus Ficaria, 

 Anemone apennina, Cyclamen persicum, and Pinguicula. 



* For a fuller treatment of the subject of Fusion see under " Phyllotaxis." 



