ens; the orders partly upon the number of styles
or stigmas, partly upon other considerations. Useful and popular as this
system was down to a time within the memory of still surviving
botanists, it is now completely obsolete. But the tradition of it
survives in the names of its classes, Monandria, Diandria, Triandria,
etc., which are familiar in terminology in the adjective terms
monandrous, diandrous, triandrous, etc. (284); also of the orders,
Monogynia, Digynia, Trigynia, etc., preserved in the form of monogynous,
digynous, trigynous, etc. (301); and in the name Cryptogamia, that of
the 24th class, which is continued for the lower series in the natural
classification.

550. =Natural System.= A genuine system of botany consists of the orders
or families, duly arranged under their classes, and having the tribes,
the genera, and the species arranged in them according to their
relationships. This, when properly carried out, is the _Natural System_;
because it is intended to express, as well as possible, the various
degrees of relationship among plants, as presented in nature; that is,
to rank those species and those genera, etc., next to each other in the
classification which are really most alike in all respects, or, in other
words, which are constructed most nearly on the same particular plan.

551. There can be only _one_ natural system of botany, if by this term
is meant the plan according to which the vegetable creation was called
into being, with all its grades and diversities among the species, as
well of past as of the present time. But there may be many natural
systems, if we mean the attempts of men to interpret and express that
plan,--systems which will vary with advancing knowledge, and with the
judgment and skill of different botanists. These must all be very
imperfect, bear the impress of individual minds, and be shaped by the
current philosophy of the age. But the endeavor always is to make the
classification answer to Nature, as far as any system can which has to
be expressed in a definite and serial arrangement.

552. So, although the classes, orders, genera, etc., are natural, or as
natural as the systematist can make them, their grouping or order of
arrangement in a book, must necessarily be in great measure artificial.
Indeed, it is quite impossible to arrange the orders, or even the few
classes, in a single series, and yet have each group stand next to its
nearest relatives on both sides.

553.