302 



OEGANOGBAPHT. 



Such fruits are sometimes called operculate, a term which is 

 also applied by some botanists to all forms of transverse de- 

 hiscence in which the upper portion of the fruit or pericarp 

 separates from the lower in the form of a lid or operculum. 



Transverse dehiscence may also occur in fruits which are formed 

 by a single ovary or carpel, as well as in the compound fruits 

 mentioned above. Thus the legumes of Coronilla, Hedysarum 

 {fig. 672), Ornithovus, &c., separate when ripe into as many 



Fig. 673. 



Fig. 674. 



Tig. 672. Fruit of a species of Hedysarum separating transversely 

 into one-seeded portions. Fig. 673. Fruit of a species of Campa- 

 nula, p. Pericarp, t, t. Pores at the sides, c, c. Persistent calyx 

 united toelow to the wall of the fruit so as to form a part of the peri- 

 carp. Fig. 674. Fruit of a species of Campanula dehiscing by pores 



at its base. 



portions as there are seeds. The separation taking place in 

 these cases has been supposed to be effected by a process called 

 solubility. Some botanists regard such legumes as formed of 

 folded pinnate carpellary leaves analogous to the ordinary pinnate 

 leaves of the same plants, the divisions taking place at the points 

 of union of the different pairs of pinnae. 



3. Porous Dehiscence. — This is an irregular kind of dehis- 

 cence, in which the fruits open by little pores or slits formed in 

 their pericarps by a process called rupturing. These openings 

 may be either situated at the apex, side, or base of the fruit, 

 hence they are described accordingly, as apicular, lateral, or 

 basilar. Examples of this kind of dehiscence occur in the Poppy 

 {fig. 426), in which a number of pores are placed beneath the 

 peltate disc to which the stigmas are attached ; in the Antirrhi- 

 num {fig. 612), where there are two or three orifices, one of which 

 is situated near the summit of the upper cell or ovary, and the other 

 (one or two) in the lower; and in various species of Campanula, 

 &c. {figs. 673 and 674). In the latter the calyx is adherent to 

 the ovary, and the pores which have a very irregular appearance 



