2 64 TEXTBOOK OF BOTANY 



the primitive condition is that found in the lily, whose 

 sepals, petals, and stamens are all separate from the ovary- 

 wall. 



274. Regular and Irregular Flowers. — The more primi- 

 tive flowers are regular ; that is, they can be cut in many 

 ways into two like halves ; a flower is irregular if there is 

 only one direction in which it can be cut into two parts that 

 are alike. An irregular flower can be said to have a right side 

 and a left side ; a regular flower is alike on all sides. Ex- 

 amples of regular flowers are those of the lily and the rose. 

 The bean, pea, violet, and lady's slipper (Fig. 159) have 

 irregular flowers. From what has now been said about the 

 different forms of flowers, we see that the same flower may 

 be primitive in some respects and advanced in others. For 

 instance, the lily is primitive in having its parts all separate 

 and in being regular in shape ; it is advanced beyond the 

 primitive condition in having both stamens and pistil in 

 the same flower, in having sepals and petals, in having its 

 parts few and arranged in circles, and in having a compound 

 pistil. The bean flower is more primitive than that of the 

 lily in having a simple pistil ; it is more advanced in its 

 irregular form, and in the union of its sepals, that of two of 

 its petals, and that of all but one of its stamens. 



275. Arrangement of Flowers. — A flower is always borne 

 at the end of a stem or branch. If a plant bears more than 

 one flower, then plainly all the flowers, or all but one, must 

 be borne on branches. Sometimes the flower-bearing branches 

 start here and there along the main stem in the axils of or- 

 dinary foliage leaves. But as a rule, if a plant has many 

 flowers, its flower-bearing branches are short and are borne 

 close together in the axils of small bracts. In this way a 

 flower cluster is foiined. The stalk of each individual flower 

 in the cluster is called a pedicel; the stalk of the whole 

 cluster, which may be the end of the main stem or may 

 be itself a branch, is called a peduncle. Both peduncle and 



