Hemsley, in his Report on
Insular Floras, says that they "are wanting in a large number of oceanic
islands where there is no true littoral flora," as St. Helena, Juan
Fernandez, and all the islands of the South Atlantic and South Indian
Oceans. Even in the tropical islands, such as Mauritius and Bourbon,
there are no endemic species, and very few in the Galapagos and the
remoter Pacific Islands. All these facts are quite in accordance with
the absence of facilities for transmission through the air, either by
birds or the wind, owing to the comparatively large size and weight of
the seeds; and an additional proof is thus afforded of the extreme
rarity of the successful floating of seeds for great distances across
the ocean.[179]

_Explanation of North Temperate Plants in the Southern Hemisphere._

If we now admit that many seeds which are either minute in size, of thin
texture or wavy form, or so fringed or margined as to afford a good hold
to the air, are capable of being carried for many hundreds of miles by
exceptionally violent and long-continued gales of wind, we shall not
only be better able to account for the floras of some of the remotest
oceanic islands, but shall also find in the fact a sufficient
explanation of the wide diffusion of many genera, and even species, of
arctic and north temperate plants in the southern hemisphere or on the
summits of tropical mountains. Nearly fifty of the flowering plants of
Tierra-del-Fuego are found also in North America or Europe, but in no
intermediate country; while fifty-eight species are common to New
Zealand and Northern Europe; thirty-eight to Australia, Northern Europe,
and Asia; and no less than seventy-seven common to New Zealand,
Australia, and South America.[180] On lofty mountains far removed from
each other, identical or closely allied plants often occur. Thus the
fine Primula imperialis of a single mountain peak in Java has been found
(or a closely allied species) in the Himalayas; and many other plants of
the high mountains of Java, Ceylon, and North India are either identical
or closely allied forms. So, in Africa, some species, found on the
summits of the Cameroons and Fernando Po in West Africa, are closely
allied to species in the Abyssinian highlands and in Temperate Europe;
while other Abyssinian and Cameroons species have recently been found on
the mountains of Madagascar. Some peculiar Australian forms have been
found represented on the summit of Kini