CHARACTERS OF NATURAL SYSTEM. 345 



upon the female organ. This mode of conformation is illustrated 

 by Fig. 129, which also explains what was meant by a superior 

 calyx (. 496). Peculiarities in the mode in which the anthers 

 open to disperse the pollen are sometimes characteristic of 

 particular orders; thus the Berberry and Laurel tribes have 

 anthers bursting by valves ; and the Heaths have anthers 

 opening by pores (. 433). But such peculiarities are found in 

 other genera, amongst orders which do not possess them ; and 

 they must not, therefore, be implicitly relied on. 



499. Of all natural characters, those furnished by the struc- 

 ture of the central parts of the flower are perhaps subject to the 

 fewest exceptions; yet these are not such as are the most evident 

 to the ordinary observer. On the number of styles, as already 

 stated, little reliance can be placed for the establishment of 

 important distinctions; but as it is less liable to vary than is 

 that of the stamens, it may often be useful in the separation of 

 genera. A much more decisive character is afforded by the 

 degree of adhesion among the carpels ; when they remain distinct 

 from each other, the ovary is said to be apocarpous (carpels 

 apart); and when they are compactly united, it is termed 

 syncarpous (carpels together). There are few natural orders in 

 which one or other of these conditions does not prevail, to the 

 entire exclusion of the other ; so that plants which bear a strong 

 resemblance in general aspect, but differ in this, may be at once 

 referred to their proper groups. The position of the ovary in 

 respect to the calyx has been already adverted to ; this character 

 is generally expressed by the terms inferior or superior ovary. 

 The presence or absence of partitions in the ovaries, is a very 

 important distinction. An ovary may be one-celled, because it 

 consists of but a single carpel; or, being syncarpous, it may 

 contain an undivided cavity, from the obliteration of the par- 

 titions, or dissepiments, originally formed by the walls of the 

 several adhering carpels. In this case the attachment of the 

 ovules, or placenta, is either central, the ovules being clustered 

 around a central column (as in Fig. 83, . 434), or parietal, 

 where they are attached to the outer wall (as in Fig. 84). 

 Varieties of structure of this nature are very important in dis- 



