THE OTTAWA NATURALIST 



Vol. XXVII. November, 1913 No. 8 



THE HAUNTS OF SOME OF OUR NATIVE FERNS. 



By A. Cosens, M.A., Ph.D., Toronto. 



A plant is dependent on its surroundings for the raw 

 materials of the food necessary for its nutrition, also the energy 

 required to manufacture this food is supplied from agents that 

 are without the body of the plant. Even the important functions 

 of pollination and seed dispersal are left very largely to the care 

 of external forces. 



A consideration of these facts leads us to see that each 

 plant has definite and vital relations to the various components 

 of its environment. These life relations are often so numerous 

 and complicated as to be only partially understood. As the 

 component factors of any environment are never stable for any 

 considerable length of time, the welfare of the individual plant 

 is dependent on the fact that it exhibits a certain degree of 

 plasticity in relation to its stirroundings. If a plant is to exist 

 it cannot present an unyielding front to the forces surrounding it. 

 A certain structure is transmitted to a plant by its ancestors ; 

 an ever changing environment tends to vary this transmitted 

 form. This feature of plant life is of such universal application 

 that we may consider a pathological condition as a variation 

 from the normal to such an extent that the life of the plant is 

 endangered. 



The study of the habitats of our native ferns presents several 

 points of interest and opens up many avenues for investigation. 

 As a rule these plants do not exhibit plasticity of structure to 

 nearly the same extent as our ordinary flowering plants. As a 

 consequence of this the conditions under which the various ferns 

 can flourish are much more restricted. 



The chief factors of the environment of these plants, 

 arranged in the order of their importance, are: light, water, 

 drainage, soil; of less importance are heat and wind. Their 

 relations to other plants will be considered in connection with 

 light, as many of the plants with which they are associated have 

 important shade producing qualities. 



