EARLY DEVELOPMENT OF FLORAL ORGANS AND 

 EMBRYONIC STRUCTURES OF SCROPHULARIA 



MARYLANDICA 



F. M. SCHERTZ 



(with plates xxvii-xxix) 



The material used in this study was collected at Evanston, 

 Illinois, in the summers of 1909 and 1915, and Bloomington, 

 Indiana, in the summer of 19 10. It was killed in medium chromic 

 acetic acid and preserved in 70 per cent alcohol. The paraffin 

 method was used, and difficulty was encountered because of the 

 hardened walls of the seed case. Consequently, the walls of the 

 seed case were dissected away, leaving the ovules attached to 

 the axile placentae, and the difficulty was greatly lessened, 

 although not entirely obviated because of the thick and hardened 

 testa which remained. 



Development of floral organs 



The order of floral development in Scrophularia marylandica L. 

 was found to be calyx, stamens, corolla, and pistil. It seems to 

 be assumed that in the majority of cyclic flowers the parts appear 

 in acropetal succession, namely, sepals, petals, stamens, and 

 carpels. In Astilbe Webb has observed that the order of succession 

 of the floral parts is sepals, inner stamens, carpels, outer stamens, 

 and petals. The origin of the petals and the stamens in S. mary- 

 landica is very similar to that of the flowers of the Primulaceae, 

 jn that the primordia of the petals appear after those of the stamens, 

 and each petal apparently comes from the dorsal surface of a young 



stamen. 



Megasporangium 



The anatropous ovules arise from central placentae and develop 

 a single integument (fig. 10). Only one layer of cells of the 

 nucellus incloses the mother cell at this stage (fig. 11), but a marked 

 change soon occurs, due to the growth of the integument. This 



441] [Botanical Gazette, vol. 68 



