143 GILLENIA TRIFOLIATA. 
ed. On the other hand, where a group of species 
is not unwieldy from its size, or deficient in dis- 
tinctive marks, the genera are made as compre- 
hensive, as natural affinity will permit. ‘The di- 
versity of structure, which exists in the flowers of 
Gentiana, or the fruit of Bunias, would be deemed 
ample foundation for constructing half a dozen ge- 
nera among the umbelliferous, leguminous, or 
gramineous orders, But as the species of the 
genera above have a strong agreement in one part 
of their fructification, as well as in general habit, 
and as no great obscurity or inconvenience results 
from keeping them together, it has not been 
thought worth while to multiply nomenclature by 
arranging them under separate titles. 
The separation of Gillenia from Spirza is one 
of those cases, upon which the botanist may hesi- 
tate long, without finding reasons strong enough 
to influence his decision. ‘The natural order to 
which they belong is remarkable for having its 
genera well defined, so that there is no necessity 
for the separation, arising from confusion or indis- 
tinctness. ‘The fruit of Gillenia is exactly the 
fruit of Spircea, and the habit of the herb in one is 
not very foreign from that of the other. There is 
nevertheless something in the irregular corolla, 
taken in conjunction with the campanulate calyx. 
