80 



PISTIL. 



Fig. 129. 



consist of several carpels, assuming a great variety of forms. It 

 is of the first importance that the student study carefully all 

 that relates to the fruit, as it is from it that the most importam 

 distinctions in classification are derived. It will be the most 

 diflScult as well as the most important subject to which his at- 

 tention will be called. By perseveringly applying the principles 

 laid down, he will soon acquire a facility in examining one of 

 the most beautiful fields of nature, which will abundantly reward 

 him for all his toil. 



132. When the ovary is composed of several carpels, the 

 carpels are arranged with the midrib placed outwardly, and the 

 margins turned inward toward the center, as 

 seen in the transverse, section of the Hibiscus 

 (Fig. 129), which is composed of five carpels, 

 with their margins meeting in the center, 

 forming a central placenta, to which the seeds 

 are attached. The divisions, which form the 

 cells of the ovary, are called dissejnments^ and 

 are of course, from w^hat we have before re- 

 marked, the inflected laminae of the leaves ; 

 and as each carpel is naturally independent 

 of the others, which compose the ovary, it fol- 

 lows that the dissepiments, however thin and 

 membranous they may be, in some cases, are in reality double. 

 All true dissepiments are necessarily vertical, and never hori- 

 zontal, since the inflected margins of leaves could not unite in 

 such a manner. The number of dissepiments is always equal to 

 the number of carpels of which the ovary is composed, and the 

 dissepiments are always alternate with the stigmas. A simple 

 ovary can have no dissepiment. Should any fruit be observed 

 with dissepiments not reconcilable to the above principles, they are 

 called spurious dissepiments. The only common one of this 

 character with which students will meet, 

 is that occurring in cruciferous plants, as 

 the Cabbage, Turnip, &c., in which the 

 expansion of the placenta forms a spu- 

 rious dissepiment, stretching from one 

 side of the ovary to the other. In some 

 cases in which the ovary is composed of 

 several carpels, there exists no dissepi- 

 ment. This arises from one of two 

 causes. In one case the edares of the 



Section of Hibiscus. 



Fig. 130. 



Parietal placenta. 



132. "When the ovary is composed of several carpels how are they ar 

 ranged ? Explain the hibiscus. ^ What are dissepiuiei is ? How mauy can 

 there be ? What are spurious dissepiments ? 



