natural Famihj of Plants called Compositce. 91 



the single ovulum is inserted at the base of the cavity. Piotcacen:, 

 however, exhibit a series of obliterations in the parts of a single 

 pistillum only. An illustration more in point, though somewhat 

 less perfect as a series, may be taken from Goodenovice, an order 

 of plants very nearly related to the class of which we are treat- 

 ing. In the greater part of Goodenovice, the ovarium is bilocular, 

 each cell having an indefinite number of seeds ; in the greater 

 number of Sccevolce, each cell is reduced to a single ovulum ; 

 while in some species of the same genus, and in all the species of 

 Dampiera, the ovarium, though retaining its external characters, 

 is reduced to a single monospermous cell, with an erect ovulum, 

 as in Compositae. The natural order CrucifenE exhibits also 

 obliterations, more obviously analogous to those assumed as 

 taking place in syngenesious plants; namely from a bilocular ova- 

 rium with two pol3'spermous parietal placentae, which is the 

 usual structure of the order, to that of Isatis, where a single ovu- 

 lum is pendulous from the apex of the unilocular ovarium. And 

 lastly in the genus Bocconia, in the original species of which 

 (D.frutescens) the insertion of the single erect ovulum has the same 

 relation to its parietal placentae, as that of Compositaj has to its 

 filiform cords, a second species (J3. cordata) exists in which these 

 placentae are polyspermous. 



My sixth observation on Compositae regards the order in which 

 the florets expand. To understand the relation this order has to 

 that of other families, it may be necessary first to make a few re- 

 marks on the more usual modes of inflorescence. 



Jt is well known that in an absolutely simple spike the expan- 

 sion of the flowers is ascendent ; that is, begins at the base of the 

 spike and proceeds regularly upwards. To this order very few 

 real exceptions occur, several of the apparent deviations being 

 connected with some degree of composition in the spike. 



X 2 la 



