and of many kinds. Sequoias (redwood, “big trees’’ of California) 
of many varieties during this era were distributed all over the 
world, both south and north, instead of being confined to their 
present small Pacific coast area. Europe, perhaps, in its Hora, 
was more like the India of today— a mixture of temperate and sub- 
tropical plants. Little is known of the North American flora just 
preceding the glacial period, but in Europe tropical and sub- 
tropical forms gradually disappeared, while temperate forms, 
such as tulip trees, poplars, and oaks, took their place. Plant 
life just before the reign of ice approximated very closely that of 
today, though it was differently distributed. Tulip trees, 
sequoias, and magnolias, once plentiful, have long been absent 
from European flora, while the ranges of many of our North 
American plants have been much altered. 
While the earlier part of this era was marked by great volcanic 
activity all over the northern hemisphere, the latter part is re- 
markable for its reign of ice. Several great ice sheets swept over 
parts of the northern and southern hemispheres, and reindeer 
lived as far south as France and Arkansas. Arctic plants came 
south during the glacial period and retreated north again during 
the periods of mild climate, or up the mountain peaks, which 
answered the same purpose, e. g . , the Alps and the White Moun- 
tains. Climatic changes resulted in the extinction of much of the 
northern flora; hence, today the southern hemisphere, where 
climatic changes perhaps were not so destructive, is a vast 
museum of relics of a flora that was once world wide, while in the 
northern hemisphere, in general, the plants are much more mod- 
ern. Somewhere during this era, possibly in Malaysia or south- 
ern Asia, man appeared, and, at the time of the ice age, he had 
discovered Europe. 
Since his coming, changes in geography, climate and plant 
distribution have been and still are in progress, as any serious 
student of these subjects will tell you. New forms of plants are 
still arising, as any plant-breeder or modern-trained student of 
plant evolution will affirm. These are no longer subjects for 
argument; from the realm of theory they have been transferred 
to that of fact. Today the oldest living things are the giant 
sequoias or redwoods of California, some of which are over"3,000 
years old. Today the plant world is largely dominated by the 
flowering plants, both in number of species and individuals. 
From this standpoint the following, list of plant species belonging 
to each of the large groups maybe interesting, though the number 
ot species sheds but little light upon the actual numerical pre- 
dominance of individuals of a species in a given flora. These 
figures are approximations: 
Flowering plants 125,000 
Conifers 450 
Ferns 3,500 
*Club-mosses and allies 500 
Mosses and liverworts 12,000 
Fungi and bacteria 64,000 
Lichens 5,500 
Algae (seaweeds, pond slimes, etc.) 14,000 
224,950 
*From the standpoint of the fossil record and those who study it, there is 
no justification, save that of custom, for considering the club-mosses as fern 
allies. If these students have correctly interpreted the rock-written records, 
the ancestors of our present day ferns and lyeopods are much further apart 
than ferns and flowering plants, at least as regards the time element. 
7 
