BROOKLYN BOTANIC GARDEN 
LEAFLETS 
Series X Brooklyn, N.Y., June 14, 1922. No. 6 
THE EVOLUTION GROUP AT THE 
BROOKLYN BOTANIC GARDEN 
There is a certain parallelism in the history of the classifica- 
tion of plants and of animals. In both cases obvious characteristics 
were first used. 
For example, whales were long classed with fishes. Later, the 
facts that they have lungs and warm blood and that they give 
milk to their young, made it clear that they are not really fishes 
at all, but nearer to animals like dogs and horses. In short, there 
is a group, mammals, having these and other characters, but 
fishes are an entirely different group. 
Similarly, locust trees were classed with trees, and peas with 
herbaceous plants. Later, the close resemblance of the flowers, 
fruits, and seeds, as well as leaves, of locusts and peas, made it 
appear that these should be included in a natural group of related 
species, namely the Pea Family. So that the old classification, 
namely, trees, shrubs, and herbaceous plants, was not a natural 
one. 
Thus, gradually, the idea of natural affinity developed as the 
basis for classification. During the nineteenth century it became 
clear that affinity really meant relationship— that the question of 
natural classification of plants and animals was really the question 
of their evolution. 
Leading facts relating to plant evolution had been demon- 
strated by Wilhelm Hofmeister, about ten years before Darwin’s 
“Origin of Species.’’ Hofmeister was for a number of years a 
music dealer in Leipzic, giving all his spare time to the study of 
of plants. It was he who first recognized the universality of the 
phenomenon of alternation of generations in all plant groups from 
liverworts to seed-bearing plants, inclusive. Hofmeister states 
facts only, without explanation. But the evidence of the essential 
unity of development of the varous groups of plants implies the 
principle of evolution. 
It appears that not only the plant world, but the whole of life, 
is really one great tree, of which the living plants and animals 
are, so to speak, the growing tips of the branches. No form is 
separate; as we go back the various forms converge, and all are 
united through the life of the past. 
What is the form of the tree of evolution? There are three 
