110 THE AMERICAN BOTANIST. 



Rosette Plants. — Late in fall and early in spring the 

 rosette plants are most conspicuous. Even the casual rambler 

 does not fail to note the multitudes of plants with their leaves 

 disposed in circles and closely pressed to the earth. It is cus- 

 tomary to assume that plants adopt this form in order to give 

 their leaves the maximum amount of illumination, and, in fact, 

 this end is secured v^hen the plants grow in open places where 

 plenty of light is available. In woods and other shady places, 

 however the rosette plants are either rare or absent. Notwith- 

 standing all this, there may still be other reasons why the 

 rosette form is a useful one to the plant. Plants, as we know, 

 need carbon dioxide for food-making. This gas is never 

 abundant in the air, but owing to its weight it is more plentiful 

 near the surface of the earth than elsewhere. Under such 

 circumstances the rosette plant clearly has the advantage over 

 taller species. Again the rosette habit is a protection from in- 

 jury by animals and storms, and in winter such plants are pro- 

 tected from sudden changes of temperature by being covered 

 with snow and dead leaves. As a matter of fact, it is likely 

 that many other plants would find it advantageous to be rosette 

 plants were it not for the struggle for light that must be main- 

 tained. 



Dominance of Flowering Plants. — Everybody is 

 aware that flowering plants are the dominant race but we sel- 

 dom realize how completely they have taken possession of the 

 earth. Mosses may form the main covering of some cold wet 

 areas in the north and ferns may occupy certain sterile regions 

 almost to the exclusions of everything else, but even here, a 

 few flowering plants creep in. In the desert, flowering plants 

 alone, are at home, in the water other species are as completely 

 adjusted to environment, and a few actually inhabit the ocean, 

 a region in which no moss, fern or conifer dares venture. In 

 looking for the reason for such diversity of form and habitat, 

 it seems scarcely too much to attribute it to the offices of in- 



