46 



STRUCTURAL BOTANY. 



a simple style, as in Linden, where these carpels are surmounted 

 by three pairs of stigmas. 



130. The compound pistil consists of the united circle of pis- 

 tils, just as the monopetalous corolla consists of the united circle 

 of petals. The union occurs in every degree, always commencing 

 at the base of the ovary and proceeding upward. Thus in Col- 

 umbine, we see the carpels (piskls) quite distinct ; in early Saxi- 

 frage, cohering just at base ; in Pink, as far as the top of the 

 ovaries, with styles distinct ; in Spring-beauty, to the top of the 

 styles, with stigmas distinct ; and in Rhododendron, the union 

 is complete throughout. 



131. To determine the number of carpels in a compound ovary 

 is an important and sometimes difficult matter. It may be 

 known, first, by the number of the styles ; or, by the number 

 of the free stigmas (remembering that these organs are liable to 

 be halved 129) ; or 3d, by the lobes, angles, or seams of the 

 ovary ; or 4th, by the cells ; or 5th, by the placenta?. But in 

 Dodecatheon, etc., all these indications fail, so perfect is the 

 union, and we are left to decide from analogy alone. 



132. The student will notice two very diverse 'modes of cohe- 

 sion in the carpels of the compound ovary. First and regularly. 

 the carpels may each be closed, as when simple, and joined by 

 their sides and fronts; as in St. Johnswort (129) and Lily (171). 

 In this case, he may prove the following propositions. 1st. The 

 compound ovary will have as many cells as carpels. 2d, The 

 partitions between the cells will be doub 1 .?, and alternate with 



