PTERIS AQUILINA AND ITS ALLIES IN NORTH AMERICA. 



By Willard N. Clute. 



THAT the name of Pteris Aquilina L. has long stood for a 

 most composite species is a fact well known to students of 

 ferns. Almost as soon as botany was established upon a 

 scientific basis, various forms of the common Bracken were 

 noted, and ever since it has been a matter of opinion as to 

 whether they should be considered as one or several species. 

 The principal reason for this difference of opinion seems due to 

 the size of the plants which prevents representative herbarium 

 specimens being made. It is most difficult to get a good speci- 

 men of this upon a single herbarium sheet, and collectors have 

 therefore taken small fronds or pinnae of larger plants, in both 

 cases failing to give an adequate idea of their shape, size and 

 habit. But while the unsatisfactory herbarium material has only 

 served to obscure the differences that exist between the forms, in 

 the field they have been observed time and again, and it may be 

 confidently asserted that few botanists would call all these forms 

 one species could they see them growing together. After allow* 

 ing for the differences due to soil, climate and latitude, the gulf 

 is still too great between the smooth, triangular fern of Eastern 

 America, the tall, woolly one of the Northwest and West and the 

 slender, irregularly branching one of the tropics, to consider 

 them one. 



For my own satisfaction I recently attempted to segregate 

 these forms, and found that they separated very naturally into 

 three groups, each with a distinct geographical range. So pro- 

 nounced was this, that it was generally only necessary to know 

 the locality on the label to say what the species was, or to see the 

 species to say in what region it was collected. 



One hundred and fifty specimens of the American Bracken 

 were examined, being those in the United States National Her 

 barium, the Herbarium of Columbia University, the Herbarium 

 of the New York Botanical Garden, the Underwood Herbarium 

 and my own collection. From a study of these, I would place 

 the North American forms as follows: 



Pteris lanuginosa Bory. {Pteris aquilina lanuginosa 

 ( Bory) Hook. Fl. Bor. Am. 2: 196. 1840). This is the common 

 form of the Northwest. It is principally characterized by the 

 stout creeping rootstock, tall fronds and densely woolly under- 

 surface. It appears also to be less inclined to the triangular than 



