110 



THE INFLORESCENCE. 



and internally lies in apposition to the corolla. Aa the bract is usually situate at a 

 distance from the flower, the calyx is in fact the external envelope (Fig. 202). In colour 



Fig. 201. Fig. 202. 



Fig. 201. The Perianth. 

 Fig. 202. -Showing the calyx, o, surrounding the corolla, 6, and forming the external covering. 



and general texture it resembles a foliaceous organ, and thus may usually be dis- 

 tinguished from the corolla. When any difficulty occurs in determining the nature of the 

 coverings of flowers, it is customary to regard the external series as a calyx, whatever 

 may be its appearance, and thus no flower can be without a calyx (except such as are 

 composed of bracts only) ; whilst many are met with without a corolla. The calyx is 

 evidently subservient to the corolla ; for, although it exceeds the latter in size up to the 

 period of the unfolding of the flower, it usually becomes relatively smaller by reason of 

 the growth of the corolla, and, in many instances, in the mature state of the flower, bears 

 no proportion to the corolla in size. The calyx is commonly continuous with the pedun- 

 cle, and is permanent ; but in many instances it is deciduous, and falls away on the 

 opening of the flower, or immediately afterwards, as in the poppy and the Cruciferce, or 

 pod-bearing plants. When the enlargement of the inner parts of the flower causes the 

 calyx to fall, it usually separates from the peduncle in one piece, and is called op&rculate^ 

 except in falling it be ruptured, when it is termed catyptrate. 



The calyx is originally formed of several distinct pieces, which are termed sepals ; and 

 when, in its after development, these adhere to each other by their sides, and become but 

 one tube, it is termed mono-sepalous ; but when they still remain distinct, each part is 

 known as a sepal, and the whole calyx is termed poly-sepalous. The sepals have all the 

 properties and analogies of common leaves, but have the superadded function of protect- 

 ing the essential parts of the flower. There is, however, one class of plants in which 

 the calyx has exceptional characters, viz., the Composite, or compound flowers. 



