88 THE STORY OF THE PLANTS. 



consisting of ono or more carpels, and con- 

 taining the embryo seeds or ovules (see Fig. 15). 

 Outside this part, and next in order, come the 

 stamenSy which are most often three or six in 

 one great group of flowering plants (the lilies), 

 and five, ten, or more in the other (the roses 

 and buttercups). The stamens produce grains 

 of pollen, which somehow or other, either by 

 means of the wind, or of insects, or of move- 

 ments on the part of the plant itself, are sooner 

 or later applied to the sensitive surface or stigma 

 of the pistil. As soon as a pollen-grain reaches 

 the surface of the stigma, it is held there by a 

 sticky secretion, and instantly begins to send 

 out what is called a pollen- tube (Fig. 16). This 

 pollen- tube makes its way down the long stem 

 or style which joins the stigma to the ovary, and 

 there comes in contact with the undeveloped 

 ovules. The ovules would not swell and grow 

 into seeds of themselves; but the moment the 

 pollen-tube reaches them, they quicken into life, 

 and begin to develop into fertile seeds. Unfer- 

 tilised ovules wither away or come to nothing, 

 but fertilisation by pollen makes them develop 

 at once into new plant colonies. 



Outside these essential organs, as botanists 

 call them, however, come, in handsome garden 

 flowers, two other sets of organs, more leaf-like 

 in appearance, but often brightly or conspicu- 

 ously coloured. The first of these sets of organs, 

 going still from within outward, is called the 

 petals, or, collectively, the corolla. Sometimes, 

 as in the dog-rose or the buttercup, the corolla 

 consists of five separate petals; sometimes, as 



