THE AVALLFLOWER 



23 



sepals are so placed that one lies next the axis 

 (posterior), and the other remote from it (anterior). 

 The two inner sepals are placed at the sides (laterally), 

 alternating with the outer two. The two inner sepals 

 are bulged out at the base ; 

 we shall see the reason for 

 this directly. In the bud 

 before it opens, the calyx 

 completely encloses all the 

 other parts of the flower. 



Inside the calyx we find 

 four floral leaves forming a 

 single ring, or whorl. These 

 are the petals, the most con- 

 spicuous part of the flower. 

 In the wild Wallflower they 

 are yellow ; in cultivated 

 specimens they are generally 

 more or less brown. Each 

 petal is broad and rounded 

 above, and tapers into a 



narrow stalk below (see Figs. 10 and 11). The four 

 petals form collectively the corolla, which is here said 

 to be polypctalous, because the petals are not connected 

 together. The petals are so placed as to alternate 

 with the four sepals that is to say, the middle of 

 each petal comes exactly opposite the space between 

 two sepals (see Figs. 12 and 13). 



Both the sepals and the petals are veined, but 

 not in such a complicated way as the vegetative 

 leaves. 



FIG. 13. Floral diagram, or 

 ground plan of the ilower of 

 Cheiranthus. a, axis of inflor- 

 escence ; s.p, posterior sepal ; 

 s.a, anterior sepal ; s.l, lateral 

 sepals ; p, the four petals ; st, 

 the six stamens (the four 

 long ones are shown connected 

 in pairs); c, the two united 

 carpels, forming the pistil. 



