252 The Phenomena of Morphogenesis 



Some species of Drosera may also readily be induced to form shoots on 

 their leaves (Behre, 1929). These develop from single epidermal cells 

 on the morphologically upper side of the lamina, at the base of a tentacle, 

 on the petiole adjacent to stomata or trichomes, or in young inflorescences 

 adjacent to glands. In Drosera binata, a species with linear leaves, the 

 young plants thus produced have roundish blades much like those of our 



Fig. 9-9. Cardamine pratensis. After a leaf is removed, plantlets develop on it from 

 preformed embryonic areas (a). ( From Goebel. ) 



own common Drosera rotundifolia. It would be interesting to find 

 whether this fact has any phylogenetic implications. 



In Begonia rex and some other varieties of begonia, shoots may be 

 induced very readily on petiole and blade by removing the growing 

 points of the shoot. Prevot (1938, 1939) found that these arose from 

 epidermal cells, but only after they had reached a certain stage of ma- 

 turity. Hartsema ( 1926 ) has described the changes that such cells undergo 



