34 



GENERATIVE STRUCTURES. 



folded when in this state, is called its form of (Estiva- 

 tion, which may be plaited, as in Convolvulacese, valvate, 

 as in Umbelliferae, &c., &c. 



184. The period or time of the opening of the petals 

 from the state of alabastrus, is termed the anthesis. 



185. The structure of the calyx and corolla is much 

 the same as that of the leaf, that of the calyx being less 

 modified, however, than that of the corolla, and having 

 much fibrous tissue ; the stomatse are small and few, as 

 are the spiral vessels. 



Generative Structures. 



186. Within the floral coverings are contained these 



organs, which consist of the outer 

 ones or male organs, called the sta- 

 mens (a), and the inner or female one 

 called the pistil ( J) . 



187. Both stamens and pistils do 

 '-a not always exist together within the 



same individual floral envelopes, but 

 when they do the flower is said to be 

 hermaphrodite, as at (fig. 29.) 



188. When the stamens and pistils 

 exist in separate flowers on the same plant, the flowers 

 are said to be monoecious, as in the Castor-oil plant ; 

 when they are placed on different plants, that is, male 

 flowers on one individual, and female ones on another, 

 they are called dioecious, as may be seen in the Willows. 



189. The stamen may be said to consist of three 

 Fig. 30. parts; the filament (a), the anther (b), 

 and the pollen (c), the last two of 

 & which are essential to the formation of 

 a a male organ, the first is not ; this may 

 be wanting, the anther then being sessile. 

 190. The filament (a), is a more or 

 less slender elongated body bearing at 

 its extremity the anther, always having 

 its origin between the base of the ova- 

 rium (d), and inner surface of the 

 corolla, or innermost floral covering. 



