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A TEXT-BOOK OF BOTANY 



united, so that the calyx is a little cup or tube (Fig. 208). 

 In any case, the calyx is useful in the bud condition of the 

 flower in protecting the more delicate parts within. Some- 

 times the sepals and the petals look so much alike that they 

 are spoken of together as the perianth, as in the common 

 lily (Fig. 274). Occasionally there is only one floral set 

 outside the stamens; and it has become the custom to call 

 it a calyx, assuming that the corolla is lacking. In still 

 other cases, there are no floral members outside the sta- 

 mens; and then the flower is said to be naked. 



133. Petals. The attractiveness of flowers usually 

 depends upon their petals, and hence their differences in 



A B C 



FIG. 208. Flower of tobacco: A., sympetalous corolla, calyx urn-like; B, tube of 

 corolla cut open and showing attachment of stamens; C, the pistil, showing 

 ovary, style, and stigma. After STRASBURGER. 



color and form are things of common experience. In many 

 flowers the petals are entirely distinct from one another 

 and can be pulled off separately. In many other flowers, 



