BROOKLYN BOTANIC GARDEN 
LEAFLETS 
THE BROOKLYN INSTITUTE OF ARTS AND SCIENCES 
Series IV Brooklyn, N. Y., October 25, 1916. No. 14 
THE ANCIENT HISTORY OF PLANTS 
The earth has been estimated to be anywhere from 25,000,000 
to 400,000,000 years old. Man, in all probability, appeared upon it 
between two thousand and three thousand centuries ago. The 
historic record, as deciphered from the remains of ancient civil- 
izations, possibly extends back seven to eight thousand years. 
This record, contrasted with the age of the earth (conservatively 
estimated at 120,000,000 years), is as a quarter-second is to the 
passing of an hour, or, as some one has more graphically put it, 
“as the dashing of a meteor through the sea of night.” The 
oldest known plant remains are probably less than half the 
earth’s age, but antedate man by millions of years. The earliest 
vegetation which the rocks have shown us, in an}' quantity, is far 
from simple in type, most of the forms being trees, shrubs, or 
woody ferns. Immense layers of rock strata still older than these 
exist, however, from which only the merest vestiges of plants 
have been taken. Hence, grounds exist for supposing these earliest 
plants to be already many stage-journeys along the road of 
evolutionary progress. Already they have an eon-old ancestral 
tree. 
During those drst ages when the earth’s crust was forming, 
land was scarce, and the seas were new and blled with fresh 
water. Hence, the drst plants were sea-born, distant relatives of 
our present-day pond-scums and slimes. As the centuries passed, 
innumerable rivers blled the seas with decomposed mineral 
matter. They lost their freshness. Only the more adaptable of 
the earlier vegetation remained, while the less adapted types ex- 
isted only in the fresh-water areas of the slowly appearing conti- 
nents. From the former, perhaps, came our present-day seaweeds; 
from the latter, our fresh-water green scums and slime's. Between 
the seaweeds, so far as the rock-written pages testify, and the 
rest of the plant kingdom, a great gulf exists— an almost entire 
absence of connecting links. A very few petrided moss and liver- 
wort fragments have been found, but these furnish practically no 
clue as to their ancestral relations, either to the pond-scums and 
seaweeds on the one hand, or to the ferns, conifers and dowering 
plants on the other. 
Mosses and seaweeds being rather delicate plants with no 
woody parts, the comparative scarcity of their petrided remains 
is rather to be expected. First, because only a relatively small 
portion of these most ancient plant graveyards have been explored 
and only vegetation most favorably placed has been preserved. 
Second, since the earliest types of vegetation arose, the land and 
sea areas which they inhabited have undergone great alterations. 
The earth’s crust has been repeatedly crumpled into mountain 
ranges and grooved into valleys, only to be rumpled and creased 
anew. Mountain chains have risen, only to sink and rise again. 
