52 PART I. — ORGANOGRAPHY. 



of the flower " (petals and sepals) are really leaves, in the great 

 majority of cases, but leaves adapted to new uses ; instead of 

 elaborating food for the plant, as is the case with ordinary 

 foliage, they subserve the functions of reproduction. Stamens, 

 also, and pistils, though they do not usually bear the remotest 

 resemblance to ordinary leaves, are really modified forms of 

 them. The fruit, too, is a modified leaf or cluster of leaves, or 

 sometimes of stem and leaves united, and the seed is an appen- 

 dage to, or an outgrowth from, a leaf. That this is the real 

 nature of the floral organs is shown, first, by the fact that they 

 occur on the stem in the same order as leaves, and develop from 

 it in the same way ; second, from the fact, that in the earliest 

 stages of their growth, they are indistinguishable from true leaves 

 in the corresponding stage of development ; third, by the fact, 

 that sometimes, when mature, they present every gradation from 

 ordinary foliage, through bracts and sepals to petals and sta- 

 mens ; and fourth, from the fact that many instances are known 

 of abnormal or monstrous flowers, where some or all of the 

 floral organs have reverted, more or less completely, to the con- 

 dition of ordinary green leaves. 



Nature of the Flower. A flower really consists, then, of a 

 short branch or stem on which leaves, modified for the purposes of 

 reproduction, are compactly arranged. Nature, requiring of it 

 other uses than those of ordinary vegetative growth, has changed 

 the form, and commonly also, the color of its parts, suiting these 

 to the requirements of the reproductive process. Its leaves, for 

 the most part, except the outer whorl, have entirely ceased to 

 perform vegetative functions, and are devoted solely to the new 

 work. Each different kind of floral leaf has also become adapted 

 to the particular work required of it, the petals and sepals doing 

 a different duty from that of the stamens, and the latter, in turn, 

 a different one from that of the pistils, but all contributing to the 

 important end of producing the seed. For this the flower exists. 

 To this object its entire mechanism, and even the beauty of its 

 corolla, its perfume and its nectar, are subservient. Even the 

 vegetative processes of the plant, which precede the flowering, 

 have largely for their object the storage of the energy necessary 

 to enable the plant to produce its flower and develop its seed. 

 The life of the plant, therefore, culminates in its flower ; it 



