POSTSCRIPT ON THE PHYSIOGNOMIC CLASSIFICATION OF PLANTS.
In the preceding sketch of a "Physiognomy of Plants," I
have had principally in view three nearly allied subjects:—the
absolute diversity of forms; their numerical proportion, i. e.
their local predominance in the total number of species in
phænogamous floras; and their geographic and climatic distribution.
If we desire to rise to general views respecting
organic forms, the physiognomy of plants, the study of their
numerical proportions (or the arithmetic of botany),—and
their geography (or the study of their zones of distribution),—cannot,
as it appears to me, be separated from each
other. In the study of the physiognomy of plants, we ought
not to dwell exclusively on the striking contrasts presented
by the larger organic forms separately considered, but we
should also seek to discern the laws which determine the
physiognomy of Nature generally, or the picturesque character
of vegetation over the entire surface of the globe, and
the impression produced on the mind of the beholder by the
grouping of contrasted forms in different zones of latitude
and of elevation. It is from this point of view, and with
this concentration or combination of objects, that we become
