(' 



ment 



THE DEVELOPMENT OF THE SEED IN THE 



PONTEDERIACEAE 



W. C. COKER 



F 



(with plate xxiii) 



A chance section of the young seed of Pontederia made several 

 years ago presented a peculiar appearance in the antipodal end of 

 the endosperm that led me to make an investigation of seed develop- 

 in this family. I have been able to study Pontederia cordala 

 and Heteranthera limosum in some detail, and Eichhornia crassipes 

 to a less extent. Collections of Pontederia have been made in South 

 Carolina and New York for several years. All my Heteranthera and 

 Eichhornia material was collected in Jamaica during August 1900. 



Examination of the literature of this family shows but one title 

 dealing with its embryology. In 1898 Smith (14) published a rather 

 full account of seed development In Eichhornia and Pontederia, and 

 gave one figure of the embrj^o sac of Heteranthera. Oddly enough, 

 he completely overlooked the interesting peculiarity that appears in 

 the endosperm of all three of the above genera, but otherwise, where 

 parallel, my work, with a few exceptions, agrees with his. As Smith 

 did not attempt to give the development of Heteranthera, I have made 

 a careful study of its ovular growth as a comparison with his work 

 on Eichhornia and Pontederia. In the last two genera I have confined 

 myself to the origin and development of the endosperm, which has 

 the same peculiarity in all three types. Hofmeister (9) devotes a 

 few lines to the development of Pontederia, but does not mention two 

 sorts of endosperm. 



heteranthera 



megaspore 



epidermis by a single tapetal layer, as is commonly the case in mono- 



cotyledons {fig. 

 first division (fig 



The spindle of this division lies near the distal 



(fig 



(fig 



293I 



[Botanical 



