If we now turn to the Flora, we shall find the aboriginal plants of
the different islands wonderfully different. I give all the
following results (Table 17/1) on the high authority of my friend
Dr. J. Hooker. I may premise that I indiscriminately collected
everything in flower on the different islands, and fortunately kept
my collections separate. Too much confidence, however, must not be
placed in the proportional results, as the small collections
brought home by some other naturalists though in some respects
confirming the results, plainly show that much remains to be done
in the botany of this group: the Leguminosae, moreover, have as yet
been only approximately worked out:--
Hence we have the truly wonderful fact, that in James Island, of
the thirty-eight Galapageian plants, or those found in no other
part of the world, thirty are exclusively confined to this one
island; and in Albemarle Island, of the twenty-six aboriginal
Galapageian plants, twenty-two are confined to this one island,
that is, only four are at present known to grow in the other
islands of the archipelago; and so on, as shown in the above table,
with the plants from Chatham and Charles Islands. This fact will,
perhaps, be rendered even more striking, by giving a few
illustrations:--thus, Scalesia, a remarkable arborescent genus of
the Compositae, is confined to the archipelago: it has six species:
one from Chatham, one from Albemarle, one from Charles Island, two
from James Island, and the sixth from one of the three latter
islands, but it is not known from which: not one of these six
species grows on any two islands. Again, Euphorbia, a mundane or
widely distributed genus, has here eight species, of which seven
are confined to the archipelago, and not one found on any two
islands: Acalypha and Borreria, both mundane genera, have
respectively six and seven species, none of which have the same
species on two islands, with the exception of one Borreria, which
does occur on two islands. The species of the Compositae are
particularly local; and Dr. Hooker has furnished me with several
other most striking illustrations of the difference of the species
on the different islands. He remarks that this law of distribution
holds good both with those genera confined to the archipelago, and
those distributed in other quarters of the world: in like manner we
have seen that the different islands have their proper species of
the mundane genus of tortoise, and of the widely distributed
American genus of the mocking-thrush, as well as of two of the
Galapageian sub-groups of finches, and almost certainly of the
Galapageian genus Amblyrhynchus.