140 Dowell : New ferns described as hybrids 



relationship to the Goldie fern is established by the presence of the 

 unmistakable dark elongated scales, while its relationship to the 

 marginal fern is shown by the character of the indusium and the 

 shape and color of the frond, — the characteristic dark bluish- 

 green upper surface and the glaucous appearance of the under 

 side. It differs from the latter by its larger size, by its thick dark- 

 brown scales, and by the position of the sori away from the 

 margin. It diners from the Goldie fern in having the fertile fronds 

 bipinnate, in the greater difference in color between the two sur- 

 faces of the frond, in having thicker indusia and the sori midway 

 between the midvein and margin. 



About a score or more plants of this fern were found along 

 the edge of a large swamp west of Springdale, near Newton, New 

 Jersey, on July 4, 1907, Dowell 4931, type. On July 22 another 

 plant {no. 50J5) of this fern was found in a different part of the 

 swamp. The marginal fern is common and the Goldie fern is 

 occasional along the edge of the swamp. 



Most of the specimens cited above are in the herbarium 

 New York Botanical Garden. 



In conclusion I may add that this paper is not intended pri- 

 marily as a contention or a defense for the theory of hybridity. 

 The principal points on which I base my opinion that these 

 ferns are hybrids, may be summed up briefly as follows : Each 

 fern has characteristics common to two species and cannot be 

 referred to any one previously described species alone, except 

 the case of Boott's fern, which has been described as a species ; 

 they have a tendency to be sterile, the sporangia being largely 

 abortive ; they occur only occasonially, and rarely in large num- 

 bers in any one locality ; they grow in places favorable for the 

 mingling of the gametes ; they are found usually associated with 

 the supposed parent species; hybrids among ferns have been 

 experimentally produced, and are known to exist. 



Port Richmond, N. Y. 





of the 



in 



