COMPOSURE 



Now look again at the entire sunflower, which you see 

 is not a single flower at all, but a flower cluster. Laying next 

 to the bright yellow circumference, is a ring of tubular flow- 

 ers that have their pistils extending beyond the anthers, 

 the tips curled back, exposing the stigmas; then comes a 

 ring of flowers with the style tips just visible, or perhaps 

 with a tiny heap of pollen on the top of the anthers; within 

 this ring, no pistils can be seen. The story now is not 

 hard to read. When the flowers first open, the brush-like 

 style is still within the tube of anthers, but it keeps on 

 growing, and, as it pushes its way through this chimney 

 lined with pollen dust, it sweeps out the pollen before it. 

 So every little flower first furnishes pollen for other flow- 

 ers, then spreads out its own stigmas. 



Now examine the bright yellow part of the sunflower. 

 Each yellow ray is really a flower, but an imperfect one. 

 There is a trace of ovary and calyx, but no true stigma, 

 and no hint of anthers. The main part is the corolla, and 

 a very peculiar one it is! At the base it is tubular, like 

 many other corollas, but for the rest of the way it seems 

 to have been split open and laid out flat, so it is called a 

 strap-shaped corolla. These outside flowers are also called 

 ray flowers. Since they have neither stigmas nor pollen, 

 they cannot help directly in seed-making, and seem to exist 

 only for show. 



There still remains the outside circle of green about 

 the sunflower; this, like the outside leaves, or bracts, of any 

 flower cluster, is called the involucre. lyet us notice the 

 sunflower's devices for seed-making, or rather for pollina- 

 tion, which must precede seed-making'. Each individual 

 flower keeps its own stigmas folded together as it sweeps 

 out the pollen, so it depends upon its neighbors for pollin- 

 ation. Sometimes the stigma must strike the pollen of 

 neighboring flowers as the style tips turn back, but the 

 flowers can surely depend on insects for carrying pollen, 



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