60 THE PLANT: A GENERAL EXTERNAL VIEW 



covering of the buds. The flowers of syringa show 

 plainly the inner parts. Of these there are two kinds. 

 The numerous slender structures with knobs at the tops 

 (sf) are stamens. The knobs themselves are anthers, and 

 they produce a yellow powder called pollen. 



-st 



FIG. ii. Flower bearing twig of syringa or mock-orange (Philadelphus coronarius) . 

 p, petals, st, stamens, s, sepal, pi, pistil of old flower whose petals and 

 stamens have fallen off ; note the four branches of the stigma. 



The central structure (pi) with four branches is the pistil. 

 The enlarged base of the pistil is, in syringa, covered by 

 the bottom part of the calyx. This hidden base of the 

 pistil is the ovary. It contains the structures which later 

 develop into seeds. The production of seeds is a complex 

 process. One of the things necessary in this process is 

 that pollen should reach the top of the pistil. We find 



