ON THE [is
ASOLEP'IADEJ.
��The vast additions to the number of species which botany is constantly receiving, while they make a natural arrange- ment absolutely necessary to the general botanist, render it at the same time proportionally difficult. For though there are still many tribes of plants easily distinguishable even by a superficial observer, yet there are others, that hitherto have been thought abundantly distinct, which can no longer be circumscribed by means of characters taken from their organs of reproduction. This is perhaps now the case with the Rubiace^e and Apocine^e of Jussieu. It is true, that to an experienced observer, it may still be practicable to refer the greater part, perhaps the whole, of these plants to their proper places in a natural series ; [13 but it is, I apprehend, no longer so, to distinguish the two orders by definitions derived from the usual source. Such at least is the opinion T have been led to form from all that I have seen published respecting them, as well as from what I have lately had an opportunity of observing in New Holland.
As, however, both these families are already too exten- sive, it becomes expedient rather to attempt their subdivision into smaller groups, which may possibly admit of more ac- curate limitation, than to unite them into one vast order, the distinguishing characters of which, could they be ob- tained, must probably be extremely vague, and clogged with numerous exceptions. Such a subdivision, it seems to me, may be easily made of the Apocineae, by employing
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