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. 



123. The third circle constitutes the androecium and is made 

 up of parts called stamens, which ordinarily have httle 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, sl 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; 

 / 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. 



