CHAP. XIV.] 
ST. HELENA. 
295 
take possession of a country and occupy it almost to the complete 
exclusion of later immigrants. The fact of so many European 
weeds having overrun New Zealand and temperate North 
America may seem opposed to this statement, but it really is 
not so. For in both these cases the native vegetation has first 
been artificially removed by man and the ground cultivated ; 
and there is no reason to believe that any similar effect would 
be produced by the scattering of any amount of foreign seed 
on ground already completely clothed with an indigenous 
vegetation. We might therefore conclude a priori , that the 
flora of such an island as St. Helena would be of an excessively 
ancient type, preserving for us in a slightly modified form 
examples of the vegetation of the globe at the time when 
the island first rose above the ocean. Let us see then w T hat 
botanists tell us of its character and affinities. 
The truly indigenous flowering plants are about fifty in 
number, besides twenty-six ferns. Forty of the former and ten 
of the latter are absolutely peculiar to the island, and, as Sir 
Joseph Hooker tells us, “with scarcely an exception, cannot 
be regarded as very close specific allies of any other plants 
at all. Seventeen of them belong to peculiar genera, and of 
the others, all differ so markedly as species from their congeners, 
that not one comes under the category of being an insular 
form of a continental species.” The affinities of this flora are, 
Sir Joseph Hooker thinks, mainly African and especially South 
African, as indicated by the presence of the genera Phylica, 
Pelargonium, Mesembryanthemum, Oteospermum, and Wahlen- 
bergia, which are eminently characteristic of southern extra- 
tropical Africa. The sixteen ferns which are not peculiar are 
common either to Africa, India, or America, a wide range 
sufficiently explained by the dust-like spores of ferns, capable 
of being carried to unknown distances by the wind, and the 
great stability of their generic and specific forms, many of those 
found in the Miocene deposits of Switzerland being hardly 
distinguishable from living species. This shows, that identity 
of species of ferns between St. Helena and distant countries 
does not necessarily imply a recent origin. 
The Relation of the St. Helena Compositce , — In an elaborate 
