FLOWEKS 



127 



adjacent cycles; that is, each petal opposite a space between 



two sepals, each stamen opposite a space between two petals, 

 and so on. Very often this alternate ar- 

 rangement of the members of successive 

 whorls is less evident besause one or more 

 whorls have more numerous or fewer parts 

 than the others, as in the case of the butter- 

 cups and crowfoots (fig. 103), roses, and 

 many other familiar flowers. In many 

 cases, as in the knotgrass (fig. 125), only 

 one set of floral leaves occurs. Such flow- 

 ers are said to lack petals and are known as 



apetalous. Some flowers, as those of the lizard' s-tail (fig. 104) 



and the willow (fig. 1 05), 



are wholly destitute of 



calyx and corolla. 



117. Staminate flow- 

 ers and pistillate flowers. 



Such flowers as are shown 



in figures 101-104, con-^ 



taining both stamens and 



pistils, are said to be 



bisexual. 1 Those which 



FIG. 104. Flower of 



lizard' s-tail, with no 



calyx or corolla 



After Engler 



contain tstamens but. not 

 pistils or pistils but not 

 .stamens, like those of the 

 willow (fig. 105), are said 

 to be itnixt'j.-uaL Many 

 families of dicotyledon- 

 ous trees and shrubs, 

 such as the Willow fam- 

 ily, the Oak family, and 

 others, have unisexual 



D 



FIG. 105. Dioecious flowers of white willow 

 (Salix alba) 



A, staminate catkin, natural size ; B, pistillate 

 catkin, natural size ; C, staminate flower, mag- 

 nified; D, pistillate flower, magnified. After 

 Cosson and De Saint-Pierre 



1 The flower itself is not sexual at all, as will appear later, but these 

 terms have come into general use, and their application to the two kinds of 

 flower seems likely to continue. 



