198 



PLANT STEUOTUEES 



. If a young anther be sectioned transversely four sporan- 

 gia will be found imbedded beneath the epidermis, a pair 

 on each side of the axis (Figs. 166, 167). When they reach 

 maturity, the paired sporangia on each side usually merge to- 

 gether, forming two spore-containing cavities (Fig. 167, B). 

 These are generally called " pollen-sacs," and each anther is 

 said to consist of two pollen-sacs, although each sac is made 

 up of two merged sporangia, and is not the equivalent of the 

 pollen-sac in Gymuosperms, which is a single sporangium. 



Fig. 167a. Various forme of stamens; A, from Solannni. showing dehiscence liy 

 terminal pores; B, from A/dutus, showing anthers witli terminal pore^ and 

 "horns"; (7, from Berben'i ; D, from Atlnrosperma, showing dehiscence by 

 uplifted valves; _£", from Aqi/U^gia, showing longitudinal dehiscence ; F, from 

 Popowia. showing pollen-sues near the middle of tlie stamen. — After Engler 

 and PuANTL. 



