THE FEMALE GAMETOPHYTE 



125 



The Plumbago type occurs not only in other species of the genus 

 Plumbago (Dahlgren, 1937; Fagerlind, 19386) but also in two other 

 genera of the Plumbaginaceae, viz., Ceratostigma (D'Amato, 19406) 

 and Vogelia (Mathur and Khan, 1941). It is so far unknown 

 outside this family. 



F 



Fig. 80. Development of embryo sac in Leontodon hispidus. A, tetrad of mega- 

 spores. B-E, dissolution of separating walls between megaspore nuclei. F, 

 mature eight-nucleate embryo sac. (After Bergman, 1935.) 



ABERRANT AND UNCLASSIFIED TYPES 



In addition to the above fairly distinct and well-established types 

 of embryo sac development, there are a few which appear to be 

 more or less isolated. The more important of them are mentioned 

 below. 



Limnanthes douglasii. The embryo sac of this plant has been 

 investigated by three different workers but without any complete 

 agreement regarding the mode of development. Stenar (1925a) re- 

 ported an Adoxa type of embryo sac and called attention to the 



