260 Mr Don on Five New Genera of Plants 
contained the loftiest trees to be met with, either in this or any of 
the fieighbouring orders. These splendid trees, which are en- 
tirely wanting in the ancient Continent, form one of the bright 
est ornaments of the forests of tropical America. Notwithstand- 
ing the apparent facility which attends the division of this order, 
on account of the size of the parts of fructification, yet none of 
the allied orders are less understood, or contain fewer genera, in 
proportion to the number of species. We are apt to place the 
Bignoniacece among the smaller tribes of vegetables ; but in 
thus viewing it,, w^e do not consider the great number of species 
remaining to be described in our Herbariums. In judging from 
the number already known to be natives of tropical America, I 
am led to think, that, when these vast countries are explored, 
the number will be very greatly augmented. 
The genus Bignonia , as constituted by Linnaeus, contained an 
assemblage of plants, which, generically considered, were widely 
different from each other. To Jussieu we are indebted, for ha- 
ving set us an example worthy of imitation, by his judicious divi- 
sion of this overgrown genus. It is the great advantage which 
a natural system possesses over all artificial methods in the study- 
ing of vegetables, that it teaches us to examine and group them 
according to their respective affinities ; and to give to the diffe- 
rent parts their relative importance in characterizing genera. 
Willdenow, and almost all'those botanists who have followed 
the Linnsean artificial method of classification, have left the ge- 
nus Bignonia untouched, without even adopting the important 
divisions proposed by M. de Jussieu. 
It is not my intention here to give a complete illustration of 
the order ; I shall confine myself merely to giving the charac- 
ters of the new genera which I have proposed. Perhaps, in a 
future number of this Journal, I may give some further illus- 
tration of this family of plants, as well as that of Sesame ee, 
to which it is nearly related; and on which I have, I trust, 
been enabled to collect some interesting materials. 
CHARACTERES GENERUM. 
Argylia. 
Bignonia sp. Lin. et Aactor. 
Calyx profunde 5-fid us, aequalis. Corolla basi tubulosa, 
superne dilatata, campanulata, subtus ventricosa, limbo 5-loba, 
