PREFLORATION. 133 



If this be so, the laws of arrangement of floral leaves 

 ought to agree with the phyllotaxy of foliage-leaves. Bot- 

 anists say that they do so agree, and the place where this 

 agreement is best seen is in the flower-bud. The arrange- 

 ment of floral leaves is an important help in determining 

 the affinities of plants. 



To observe this arrangement, make a horizontal sec- 

 tion of a bud just before it opens. Be careful to make 

 the section in the upper part of the bud, where the petals 



FIG. 398. FIG. 399. FIG. 400. 



and sepals are most easily 'seen. Observe with a magni- 

 fying-glass the disposition of parts, and compare your ex- 

 amples with the modes of arrangement here pictured and 

 named. 



In VALVULAR prsefloration there is no overlapping of 

 parts. The edges of the sepals and petals just meet, and 

 the flower is almost always regular (Fig. 398). 



INDUPLICATE is a form of valvate aestivation, in which 

 the edges are turned slightly inward, or touch by their 

 external face (Fig. 399). 



REDUPLICATE is a form of valvate aestivation, in which 

 the edges turn slightly outward, or touch by their internal 

 face (Fig. 400). 



In the CONTORTED arrangement, each leaf overlaps its 

 neighbor, and the parts seem twisted together (Fig. 401). 

 It becomes CONVOLUTE when each sepal or petal wholly 

 covers those within it. 



In IMBRICATE aestivation, the parts of a floral circle, 

 usually five, are placed as seen in Fig. 402. The first leaf 



