106 



PEACTICAL BOTANY 



FIG. 93. Apetalous flower of buckwheat (Fagopyrum 

 esculentum) 



A, flower ; B, section of flower. Both somewhat magnified. 

 After Marchand 



Frequently the arrangement of the floral organs differs from 

 that just described by reason of the absence of one or more 



sets of organs or 

 from the multi- 

 plication of the 

 whorls. In the 

 buckwheat, for 

 example (Fig. 

 93), only one 

 whorl surrounds 

 the stamens and 

 pistil. In such 

 cases it is usual 



to assume that the missing flower leaves are the petals, and 

 the flower is said to be apetalous (without petals). Sometimes 

 neither sepals nor petals are found (Fig. 94). On the other 

 hand, many flowers have 

 both calyx and corolla, 

 with the number of petals 

 equal to that of the 

 sepals, but with indefi- 

 nitely numerous stamens, 

 as in buttercups. 



96. Unisexual flowers. 

 Among many families 

 of plants the flowers do 

 not contain both stamens 

 and pistils. One kind of 

 flower has stamens only, 

 and is called a staminate 

 flower, while the other A 



kind has pistils only, and FlG> 94 D io3C i us flowers of white willow 

 is called & pistillate flower (Salix, alba) 



(FigS. 94 and 96). Such A, staminate catkin, natural size; B, pistillate 

 flowprs arp <*airl tn hp catkin, natural size; (7, a staminate flower, 

 lowers are Said to be magnified; A a p is tmate flower, magnified. 



Unisexual Or diclinous. After Cosson and De Saint-Pierre 



