144 



THE FLOWER. 



[CH. XI 



the buttercup five floral leaves spring from the axis at 

 practically the same level ; and five others form a second 

 group just above the first. In fig. 63 B two of the lower 

 group 1 are visible, they are seen to be smaller than the 

 leaves of the inner group (of which three are shown) and 

 are also distinguishable by their hairy outer surface. This 

 outer group is known as the calyx, and each of its con- 

 stituent leaves is a sepal. The inner group of leaves is 

 known as the corolla, and is made up of petals. 



It is important to note that the petals are arranged 

 alternately with the sepals : in other words the petals are 

 not vertically above the sepals, but each petal springs 

 from the floral axis on a line which if prolonged down- 

 wards would pass between the points of origin of two 

 sepals. This arrangement will be understood from fig. 64, 



FIG. 64. 



FLORAL DIAGRAM OF THE PEACH. 

 (From Le Maout and Decaisne.) 



1 In many flowers the floral leaves are spirally arranged on the axis, 

 just as the foliage leaves are so disposed on the stem. This may be the 

 case even when the floral leaves are obviously divided into groups, the 

 members of which appear to spring from the axis all at one level. Such 

 groups are conveniently called whorls, although this term strictly implies 

 that the members are not spirally disposed, 



