A species of Zamia (_Zimites_) grew in the swamps,
with _Potamogeton, Sparganium_, and _Menyanthes_; while ivy and
villes twined around the forest-trees, and broad-leaved ferns
grew beneath their shade. Even in Spitzbergen, as far north as
lat. 78 deg. 56', no less than ninety-five species of fossil plants
have been obtained, including _Taxodium_ of two species, hazel,
poplar, alder, beech, plane-tree, and lime. Such a vigorous growth
of trees within 12 deg. of the pole, where now a dwarf willow and a
few herbaceous plants form the only vegetation, and where the
ground is covered with almost perpetual snow and ice, is truly
remarkable."
Taking the Miocene flora as a whole, Dr Heer concludes from his
study of about 3000 plants contained in the European Miocene
alone, that the Miocene plants indicate tropical or sub-tropical
conditions, but that there is a striking inter-mixture of forms
which are at present found in countries widely removed from one
another. It is impossible to state with certainty how many of the
Miocene plants belong to existing species, but it appears that
the larger number are extinct. According to Heer, the American
types of plants are most largely represented in the Miocene flora,
next those of Europe and Asia, next those of Africa, and lastly
those of Australia. Upon the whole, however, the Miocene flora
of Europe is mostly nearly allied to the plants which we now
find inhabiting the warmer parts of the United States; and this
has led to the suggestion that in Miocene times the Atlantic
Ocean was dry land, and that a migration of American plants to
Europe was thus permitted.
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