262 TEXTBOOK OF BOTANY 



arranged, not spirally, but in a definite number of circles. 

 Thus the lily has one circle of sepals, one of petals, two 

 circles of stamens, and one circle of macrospore leaves which 

 have united to form a single pistil. 



In the more advanced monocotyledons, the number of 

 each sort of part has usually become three or six ; in the more 

 advanced dicotyledons, it is most commonly four or five or 

 a multiple of four or five. In a particular flower, some of 

 the parts may remain numerous although the other parts 

 have become few and fixed in number; thus, the apple 

 flower has five sepals, five petals, and usually five macrospore 

 leaves, but many stamens. In other flowers, as in those of 

 the bean and lily, all the parts are few and fixed in 

 number. 



273. Union of the Parts of a Flower. In the more primi- 

 tive flowers, all the parts are separate from one another ; 

 the sepals are attached to the flower-stalk below the other 

 parts; the petals (if there are any) are next above the 

 sepals, the stamens are next, and the attachment of the 

 pistil or pistils is at the end or top of the stalk. This is the 

 arrangement in a buttercup. But many flowers have de- 

 parted from this condition, because some of their parts have 

 grown together more or less. Often the petals are united 

 into a tube for part of their length, as in the cucumber 

 flower, or for their whole length, as in the morning-glory 

 and the petunia. In flowers with united petals, the sepals 

 are usually also united with one another in the same way ; 

 this is the case in the cucumber flower. Sometimes, as in 

 the Roman hyacinth, both sepals and petals unite to form 

 a single tube. 



Often some or all of the stamens are connected with one 

 another. For instance, in the flower of the sweet pea, as 

 in that of the bean, nine of the ten stamens are grown to- 

 gether by their filaments. All of the many stamens of the 

 hollyhock or of the cotton are united by their filaments into 



