302 REGULAR ARRANGEMENT OF THE PARTS OP FLOWERS 



such leaves ; and they are then always seen to present their hol- 

 lowed faces towards each other, in the manner seen at b. This 

 precisely corresponds with the position of the true carpels shown 

 at d ; in which the suture or line of junction of the two edges, 

 of each carpel is opposite to that of the other. If any further 

 proof were required, of the carpel being a transformed leaf, it is 

 afforded by the fact that, in Roses, Anemonies, Ranunculuses, 

 and other such flowers, which are liable to have their stamens 

 converted into petals, or into true leaves, the carpels not unfre- 

 quently undergo the same changes, so that the whole flower is 

 metamorphosed into a bunch of leaves, which are still arranged, 

 however, on exactly the same plan with the parts of the real 

 flower. 



463. The usual arrangement of these parts corresponds pre- 

 cisely with what was formerly stated, of the disposition of the 

 leaves (. 303.) When the spiral, which may be regarded as 

 their regular mode of arrangement, is converted into a whorl or 

 verticil, by the non-development of the intervening part of the 

 axis, and two or more of these whorls succeed one another, their 

 several leaves do not correspond, in the direction in which they 

 issue from the stem ; but are so placed, that the leaves of each 

 are above or below the intervals between the leaves of the 

 other. When this is the case, the whorls are said to alternate 

 with each other. Now the regular flower may be considered as 

 made up of five such whorls, arising from nearly the same part 

 of the axis ; and they are disposed alternately with each other. 

 Thus, the sepals of the calyx alternate with the bracts; the 

 petals of the corolla alternate with the sepals, and are opposite 

 to the bracts ; the stamens alternate with the petals, and are 

 opposite to the sepals ; and the carpels alternate with the 

 stamens, and are opposite to the petals. 



464. This very simple law, regulating the position of the 

 parts of the flower, is apparently subject, however, to many 

 exceptions ; but these all arise from the interference of other 

 causes. For example, the number of parts may be so much in- 

 creased, that they cannot be all arranged in one whorl, and they 

 then form additional verticils ; which, however, still follow the 



