8 REPRODUCTIVE ORGANS. CHAP. 111. 



in St. John's-wort ; and if it remains after the 

 stamina have fallen, it is said to be permanent or 

 persistent, as in the Star of Bethlehem. 



The colour of the corolla is in some flowers a 

 beautiful white, as in the elegant blossoms of the 

 Guelder Rose and Magnolia ; in some it is red, as 

 in many of the Roses ; in some it is yellow, as in 

 Caltha palmtrls ; in some it is blue, as in German- 

 der Speedwell ; in some it is violet, as in common 

 Nightshade ; and in some it is purple, as in Fox- 

 glove. 



How dis- The corolla, like the calyx, is not at all absolutely 

 froouhe 6 essential to the botanical notion of a flower, and is ac- 

 calyx * cordingly sometimes wanting. When present, how- 

 ever, it affords also, like the calyx, the most unexcep- 

 tionable marks of generic discrimination, arising 

 either from the mode of its insertion, or from thepecu- 

 Jiarities of its figure, or from its character, as consist- 

 ing of one or more petals. If the calyx and corolla 

 (the exterior and interior envelopes of the flower) are 

 both present, the flower is said to be complete, 

 and the distinction between the two envelopes is 

 obvious. 



But if one envelope only is present, as in the 

 Tulip and liliaceous plants in general, and the other 

 altogether wanting, the flower is then said to be in- 

 complete ; and a question naturally arises with re- 

 gard to the true character of this solitary envelope : 

 Is it a calyx or corolla ? The solution of this ques- 

 tion has been the subject of a great deal of botanical 



