SPERMATOPHYTES : ANGIOSPERMS 



361 



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. 320, 321). When they reach 

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

 gether, forming two spore-containing cavities (Fig. 321, 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 Gymnosperms, which is a single sporangium. 



Fig. 322. Various forms of stamens: .-1, from Solatium, showing dehiscence by 

 terminal pores; B, from Arinitus, showing anthers with terminal pores and 

 "horns"; C, from Berberis ; D, from Atherospenna, showing dehiscence by 

 uplifted valves; E, from Aquilegia, showing longitudinal dehiscence ; F, from 

 Popoina. showing pollen-sacs near the middle of the stamen.— After Engler 

 and Prantl. 



