MORPHOLOGY OF LEAVES AND FLOWERS 



615 



Kg. 475 I Fig. 475 II Fig. 475 III 



Fig. 475. Flower of Milkweed, showing the peculiar hooded and horned stamens. 

 I. Flower. II. Stamen. III. Pistil with adhering pollen masses. IV. 

 Pollen masses or pollinia. 



(After Thom«.) 



THE DEVELOPMENT OF A STAMEN AND ITS FUNCTION IN SEED 



PRODUCTION. 



Every one knows that the pollen produced by the stamens has 

 an important part to play in seed production. It is for this rea- 

 son that the stamen is considered one of the essential organs of 

 the flower. 



There is so little variation in the general dfevelopment of stamens 

 in the higher seed plants that the history of a stamen from any 

 weed will suffice for all. 



A mature stamen consists of a stalklike portion, the filament, 

 and the pollen-bearing portion, the anther, which is borne on top 

 of the filament. The filament may be variously modified or even 

 wanting. 



Fig. 476. Cross sectiop of anther showing pollen sacs. A. pm, pollen mother 



cells ; t, food cells. B. Pollen grains mature and being shed. 



(From Coulter, after Baillon & Luerssen.) 



An anther appears distinctly four lobed. If a cross section of a 

 young anther be made, four distinct regions will be found, one in 

 each lobe or a pair on each side of the axis. These four distinct 



