IPOMOEA BATATUS 



489 



The fruit is a globose capsule usually consisting of a two-loculed 

 ovary with two ovules in each cell. False septa may divide the 

 locules so that the fruit appears to be a four-celled, four-valved 

 capsule with a seed in each locule. The anatropous ovules are 

 more or less basal and develop from axial placentae at the inner 

 angle of each cell. The seed is approximately 3 mm. in its greatest 

 dimension, black, somewhat flattened, with one surface angular 

 and the other roughly con- 

 vex. The seed coat is 

 tough and corneous, and 

 nearly impervious to water. 

 The internal structure is 

 similar to that described 

 by Lubbock (9) for other 

 species of Ipomoea and 

 Convolvulus. The micro- 

 pyle is deeply invaginated 

 so that a tubular cavity is 

 formed above the hilum 

 and the inner portion of 

 the seed coat is infolded 

 to such an extent that the 

 apical end of the seed is 

 two-chambered. This sep- 

 tum probably determines 

 the configuration of the ^ . j- ■ , j ■ u ■ c 



•^ . Fig. 150. A, median view or seed with portion or 



two deeply bilobed COty- cotyledons cut away to show septum; B, ventral 



ledons TFiff i^O A B^ view; C, dorsal aspect of dissected embryo, after 14 



u J ' 1' hours ; D, ventral aspect : an, auricle ; cot, cotyle- 



As tne embryo develops, jon; /dr/', hypocotyl ; ;«/V, micropyle; ri?/?, septum. 



the hypocotyledonary axis 



occupies the tubular cavity formed by the invagination of the 

 micropyle. The development of the lateral lobes of the coty- 

 ledons, after the apex of each has come in contact with the in- 

 truded septum, results in the pushing of half of each cotyledon 

 into one of the lateral chambers and the formation of well- 

 defined auricles which lie on either side of the hypocotyl. As 

 the cotyledonary lobes continue to grow, they become transversely 

 folded. The dorsal and ventral aspects of the dissected embryo 

 are shown in Figure x5o, C and D. The seeds are albuminous 

 and a pulpy endosperm overlies the folded cotyledons. Upon 



