14 MORPHOLOGY OF SPERMATOPIIYTES 



It is of interest to note that numerous stomata are found on 

 the sporangium wall of Cemtozamia, Encephalartos, and Stan- 

 geria, and doubtless in other genera. They are found on the 

 wall which is opposite to the slit of dehiscence that is, toward 

 the sporophyll. Stomata also occur upon pollen sacs of certain 

 Angiosperms, but so far as recorded not upon the sporangia of 

 Pteridophytes. 



The development of the sporangia, their large output of 

 spores, their arrangement in sori, their several-layered wall, and 

 their dehiscence, are all characters suggestive of Marattiaceae; 

 while the chief resemblance to Angiosperms is found in the 

 hypodermal archesporium. 



THE MEGASPORANGIUM 



In most cases a definite ovulate strobilus is organized, which 

 is terminal in Cycas, and possibly so in the other genera (Figs. 

 11, 12, 13). In Cycas the axis of the strobilus continues 



FIG 11.- 



* revoluta, ovulate strobilus. From photograph taken in Lincoln Park, 

 Chicago. 



growth after the seeds have been formed, produces foliage 

 leaves, and finally organizes another strobilus. In all other 

 cases, including the staminate strobilus of Cycas, a strobilus 

 stops the growth of the axis. The size of the ovulate strobilus 



