BKACTS AND FLORAL LEAVES. 



75 



grains are developed. These escape, when ripe, as a yellow dust. 

 When the androecium is removed there still remain behind a lot 

 of little spirally arranged green bodies, the carpels, called alto- 

 gether the pistil or gynoecium. Within each carpel is a cavity 

 containing a minute oval body known as an ovule. In overblown 

 specimens all the structures above described fall off except the 

 carpels, which enlarge considerably, and form the buttercup fruit, 

 while the ovules become seeds. Sepals, petals, stamens, and 

 carpels are alike floral leaves, though they depart more and more 

 widely from the type presented by the foliage leaf. They will be 

 dealt with in the above order, but it is first desirable to consider 

 some points concerning the flower as a whole, and the receptacle. 

 The inflorescence or arrangement of flowers upon the plant 

 varies considerably in different cases. Since flower-buds are just 

 as much young shoots as leaf-buds, we may expect to find them 

 developed in corresponding situations, and this is actually the 



Fig. 30.— Flower of Buttercup. A. a vertical section ; c. sepals; pe. petals; e. stamens; 

 pi. carpels. B. extrorse anther seen from outside, showing lobes. C. anther seen 

 from inside. D. section of carpel ; 0. ovary ; s. stigma ; g. inverted ovule. E. 

 section of an achene ; /. pericarp ; t. seed-coat ; p. endosperm ; e. minute embryo. 



case. In very rare cases, e.g., tulip, there is a single flower on 

 the end of the main stem. The plant is then uniaxial. The vast 

 majority of flowers, however, belong to axes of higher order. 



The different kinds of inflorescence are classified under two 

 headings, racemose and cymose, corresponding exactly to the 

 methods of monopodial branching described on p. 24. (1.) The 

 racemose or indefinite type possesses lateral flowers, which, in 

 the simplest cases, e.g., pansy, spring from the axils of ordinary 

 leaves. The growth in length of a stem ceases when a flower- 

 bud is developed at its end, and this type is called " indefinite " 

 because the axis ends in an ordinary leaf-bud, and therefore 

 continues to elongate. The simplest case of (2.) the cymose or 

 definite type is seen in the tulip and some other cases, where, 

 as mentioned above, the main axis develops a flower-bud at its 

 end and ceases to elongate. Xo other flower is developed. If 



