FLOWERS 



49 



All the flower parts mentioned above, in the representative 

 flower, are attached to the end of the flower stalk, the 

 receptacle or torus. The calyx and corolla taken together 

 constitute the perianth. 



We shall see that there are many different sorts of flowers 

 in the families of seed plants. They differ widely in size, 

 form, color, and in the shapes of the various parts. 



Development of the Flower. — The primordia of flower 

 parts arise as protuberances from the young receptacle (Fig. 

 15). As a rule, the sepals, petals, stamens and carpels 



Fig. 22. — Cross-section of a mature lily anther. The pairs of pollen cham- 

 bers unite to form two pollen sacs, filled with pollen grains; s, modified epi- 

 dermal cells at line of splitting. (From a Text-book of Botany by Coulter, 

 Barnes, and Cowles. Copyright by the American Book Company, Publishers.) 



appear in the order named, as described in the case of the 

 apple flower on page 366. This order of floral succession is 

 said to be acropetal. Although this is the prevaiHng order, 

 there are different types. For example, in some mustards 

 the petals are the last to appear, and in some roses the carpel 

 primordia appear before the stamens. 

 Stamens. — Ordinarily, the anther is held upon a filament 



