THE FLOWER 



57 



anth. Neither calyx nor corolla are essential parts of the flower. 

 One or both may be wanting without thereby impairing the 

 function of the flower. 



1 23 . The third circle constitutes the andrcecium and is made 

 up of parts called stamens, which ordinarily have little resem- 

 blance to leaves. There is usually a slender stalk (the filament) 



FIG. 27. Diagrams of floral structures. A shows the relations of the floral 

 parts in a hypogynous flower; B, the same in a perigynous flower; C, the same in 

 an epigynous flower; D, a stamen; E, a simple pistil in longitudinal section; F, 

 the same in cross section; G, transitional forms between true petals (left) and 

 true stamens (right); H, slight union of two carpels to form a compound pistil; 

 7 and /, union of carpels more complete; K and L, cross sections of compound 

 pistils, of three carpels. In B: a, stamen; b, petal; c, sepal; d, pistil; e, receptacle; 

 /, pedicel. In D: a, anther cell; b, connective; c, filament. In E: a, stigma; 

 b, style; c, ovules; d, ovary. 



at the summit of which is attached a double sack-like organ 

 (the anther) containing a powdery or granular substance (the 

 pollen) . 



124. In certain flowers the stamens bear a close resemblance 

 to a leaf. In such cases the filament is leaf-like in form and the 

 cells of the anther are borne on its edge. The number of sta- 

 mens is frequently the same as, or a multiple of, the number 

 of parts of the calyx or of the corolla, but it may vary from one 

 to many. 



