Natural Orders .] 
APPENDIX. 
563 
RUBIACEJ3.* As this order is now constituted it appears to 
me impracticable to distinguish it from Apocineae, by characters taken 
from the fructification alone ; and even if the Stellatae or Asperuleae be ex- 
cluded, and the remarkable stipulation of its remaining sections be taken into 
account, it will not then, perhaps, admit of a definition entirely free from 
exceptions. It must also, I think, be allowed that Rubiaeeae, Apocineae, 
Asclepiadese, and certain genera at present referred to Gentianeae, form but 
one great natural class. In this class the leaves are uniformly simple, per- 
fectly entire, and, with a very few exceptions, occurring in Asclepiadeae and 
Apocineae, also opposite ; while in the parts of fructification there are hardly 
any characters that are not liable to exceptions, unless the monopetalous 
regular corolla, and stamina alternating with its laciniae and not exceeding 
them in number. 
The order Rubiacece, admitting it as it is at present established, is 
chiefly aequinoctial. 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 Pomace , is chiefly 
found in the principal parallel. Jussieu is very unwilling to admit these 
two genera into Rubiaeeae, 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 importance as to 
separate plants into different natural orders, it is sufficient to advert to 
Proteaceae, Amaranthaceae, and Epacrideae, all of which contain genera 
with one, two, and even an indefinite number of seeds : and as Opercula- 
riae entirely agree with many genera of Rubiaeeae in other points of struc- 
ture of fructification, in habit, and especially in their remarkable stipula- 
tion, I think there can be no doubt that they ought to be referred to the 
same order, of which they may form a section, characterized not only by its 
single-seeded ovarium, but by the peculiar dehiscence of its compound 
fruit. 
APOCINEJ3.1’ I have already observedX that this order is very nearly 
* ,/uss. gen. 196. 
f Prodr. ft. nov. holt. 465. Apocinearum pars, Juss, gen. 143. 
t Werner, soc. transact. 1. p. 12. 
