174 Part III. Chapter 1. 
Evolution of the forests. The great feature of the Cretaceous period was 
its dicotyledonous forests (see Fig. 2) and an enumeration of the genera is 
sufficient to show the richness of the flora at this time.. As the remains are 
largely leaves and fruits, trees and shrubs predominate in the lists given by 
phytopaleontologists, but the presence of arborescent species and ferns pre- 
supposes the presence of numerous herbaceous plants which owing to their 
herbaceous, or succulent character failed of preservation. 
But the Miocene period is of greatest interest to the phytogeographer. 
Much of our knowledge has been obtained through the researches of GOEPPERT, 
HEER, LESQUEREAUX, UNGER, ETTINGSHAUSEN, STARKEY GARDNER, WARD, 
Gray and KnowLToNn. We know that during the close of the Cretaceous, 
the Eocene and Miocene periods a forest of great denseness existed in nor- 
thern North America, extending far north into the arctic regions. This flora 
consisted of a great variety of trees and shrubs found in North America today, 
and in addition of many related genera and species which are at present ex- 
tremely local in distribution, or have become extinct. Many of the descendants 
of this flora exist, as will be shown later in this chapter, in widely separated 
districts, such as Japan, China, eastern America, Pacific America and Europe. 
HEER in 1874‘) called attention to the fact that out of the 353 plants known 
from the Miocene flora of the arctic region the following extended from Green- 
land to the Mackenzie River: 7arodium distichum, Glyptostrobus Ungen, 
Sequoia Langsdorfü, Populus arctica, Salic Raeana, Corylus Macguarrü, 
Platanus aceroides, Hedera Macclurii existed in Alaska and on the island of 
Sachalin, off the north coast of Japan, while Alzus Kefersteinü, Betula prisca, 
Corylus insignis, Carpinus grandis, Castanea Ungeri and Juglans acumınata 
grew in Spitzbergen, Greenland and Iceland ?). 
The relict Miocene flora. There are Tertiary genera of plants not found 
in Europe today which are prominent elements of the North American flora 
and which remain as relicts of that Miocene forest flora which spread acrosS 
the northern hemisphere into Europe and Asia°). Such genera, as Lirio- 
dendron, Magnolia, Vitis, Liquidambar, Sassafras, Aralia and Nyssa, exem 
plify the fact which GRAY and LESQUEREUX emphasized that the present flora 
of northeastern America shows the strongest relationship to the Miocene flora 
of Greenland and North America including the territory west of the Mississippi. 
Many North American trees at present existing can be positively identified 
with Tertiary species. Such a similarity exists between the following list due 
to ENGLER*®): 
ı) HEER: Nachträge zur miocenen Flora Grönlands, Kongl. Svenska Vetensk Acad. Handl. 
1874. XII. 2. 
2) ENGLER: Versuch einer Entwickelungsgeschichte der Pflanzenwelt. 1. Theil, 1879, pp- 3+ 
3) GRAY, Darwiniana 1877 p. 228. — ENGLER: Grundzüge der Entwicklung der Flora Europas 
seit der Tertiärzeit. Botan. Jahrbücher Bd. XXXVI, Heft 4, Beibl. Nr. 81, pp- 5—27- 
4) ENGLER: Versuch einer Entwickelungsgeschichte der Pflanzenwelt, ı. Theil, p- 5: 
