COROLLA. 71 



to the plant, and Imving more the appearance of leaves. Al- 

 though the ahove may be considered as desif^nating this or- 

 f^an in most plants, yet there are numerous exceptions to it. 

 The first part of the definition, that it is the outer covering, 

 is the only characteristic that never varies. It is some- 

 times even more brilliant in its colors, and larger than the 

 corolla itself, and instead of being more permanent, in some 

 species of plant, it falls even before the corolla expands, but 

 these are exceptions to a general fact. 



79. When the calyx consists of a single piece it is 

 said to be gamosepalous, a term invented to indicate the 

 union of several sepals in forming the calyx. When it 

 is composed of several distinct leaves, it is called Polysepa- 

 lous. In the gamosepalous calyx, that portion formed by the 

 union of the sepals is called the tube fig. 65, a the expansion 



at the top (b) is called the limb. If the calyx 

 takes its rise below the ovary or seed ves- 

 sel, it is said to be inferior, if from the sum- 

 mit of the ovary, it is said to be superior. 

 The origin of the calyx in both cases is un« 

 doubtedly the same, that is, from beneath the 

 ovary ; but in the superior calyx it becomes firmly united to 

 the ovary and forms a part of it, as in the Apple. 

 The Rose and a few other plants form exceptions to the 

 above, as what appears to be the cup-like calyx of the 

 Rose is now considered, and correctly too, ^ an expansion or 

 hollowing out of the summit of the pedicel, in which the calyx 

 is situated. 



80. Corolla, — As we above remarked, when there are two 

 whorls of floral envelops, the interior is called the Corolla. 

 The divisions of the corolla are always alternate with those 

 of the calyx, a necessary consequence of the law laid down 

 in par. 76, that the bases of contiguous whorls of leaves are 

 alternate. The individual leaves of which the corolla is com- 

 posed are called petals, and if the petals are united by their 

 margins forming a /u6e, the corolla is said to be gamopetalovs, 

 li they are distinct it is called polypetahms. — 

 The orifice of the tube is called the throat. 



81. The forms assumed by gamopetalous co- 

 06 A rollas are various and have .|:e- 



ceived characteristic names, the 

 principal of which are the follow- 67 

 ing: 



1, Rotate having a very short 

 tube with a spreading limb, as in 

 fig. 66. 



