EDITORIAL. 



The absence of the boulder fern (Dicksonia) from 

 a triangular area south of the great lakes, discussed by 

 Dr. Hill in this issue may possibly be accounted for by 

 the fact that this area practically coincides with the 

 northeastward extension of the prairie region. The 

 boulder fern is primarily a plant of elevated and broken 

 regions and it is quite possible that the level prairie 

 does not form a congenial home for it. North and 

 south of this area the region is hilly and here and 

 there the fern is reported. It would be extremely in- 

 teresting to know if this fern is ever found in true 

 prairie surroundings and if any of our readers know 

 of such instances we hope they will send us the in- 

 formation. The study of ecology is rapidly explain- 

 ing the puzzles of plant distribution. A large number 

 of factors enter into the make up of a suitable habitat. 

 Sun and wind, cold, moisture, nature of the soil, com- 

 petition of other plants, even the time of the year 

 when the most rain falls must be considered. Doubt- 

 less the prairie region presents some features not to the 

 boulder ferns liking and it is accordingly absent from 

 such areas. 



* * * 



It has been common, in recent years, to interpret 

 every variation from the normal in ferns as an evidence 

 of hybridization and in consequence a considerable 

 number of forms have been described as hybrids. To 

 the supporters of the hybridization theory a paper by 

 W. D. Hoyt in the Botanical Gazette for May must 

 come as a rude shock. This author, after rather ex- 

 tended experiments, maintains that hybrids among 

 ferns are extremely rare and he even casts doubts upon 

 the conclusions drawn by Miss Slosson in her attempts 



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