36 GENERAL REMARKS ON THE 



668] RUBIACE^.^ As this order is now constituted it 

 appears to me impracticable to distinguish it from Apocinese, 

 by characters taken from the fructification alone ; and even 

 if the Stellatse or Asperulese be excluded, and the remark- 

 able stipulation of its remaining sections be taken into ac- 

 count, it will not then, perhaps, admit of a definition en- 

 tirely free from exceptions. It must also, I think, be allowed 

 that Rubiacese, Apocinese, Asclepiadese, and certain genera 

 at present referred to Gentianese, form but one great natu- 

 ral class. In this class the leaves are uniformly simple, 

 perfectly entire, and, with a very few exceptions, occurring 

 in Asclepiadese and Apocineae, also opposite ; while in the 

 parts of fructification there are hardly any characters that 

 are not liable to exceptions, unless the mouopetalous regu- 

 lar corolla, and stamina alternating M'ith its lacinise and not 

 exceeding them in number. 



The order Bubiace^s, admitting it as it is at present 

 established, is chiefly equinoctial. In Terra Australis its 

 maximum is also within the tropic, where, however, it is 

 not very numerous ; and the most remarkable Australian 

 part of the order, consisting of Opercularia and Fornax, is 

 chiefly found in the principal parallel. Jussieu is very un- 

 willing to admit these two genera into Rubiacese, and is 

 rather disposed to consider them as a distinct family ; 

 chiefly on account of their single-seeded ovarium. To 

 prove that this character alone, however, is not of such im- 

 portance as to separate plants into different natural orders, 

 it is sufficient to advert to Proteacese, Amaranthacese, and 

 Epacrideee, all of which contain genera with one, two, and 

 even an indeflnite number of seeds ; and as Opercularise 

 entirely agree with many genera of Rubiaceae in other 

 points of structure of fructification, in habit, and- especially 

 in their remarkable stipulation, I think there can be no 

 doubt that they ought to be referred to the same order, of 

 which they form a section, characterised not only by its 

 single-seed ovarium, but by the peculiar dehiscence of its 

 compound fruit. 



1 Juss. gen. 196. 



