George Edward Davenport

“ It is sometimes difficult to distinguish small specimens of Cheilanthes lanugillosa from Notholœna Parryi, and not an uncommon thing for fronds of Woodsia obtusa and Cystopteris fragilis to become mixed through their close resemblance, and if this occurs among species belonging to entirely different genera, how much more likely is it to occur among closely related species. So that I cannot see why any argument drawn from such resemblances should have more weight in this instance than in those mentioned.
Few ferns are really more distinct than A. Boottii. ”

“ Var. Boottii, I have always been inclined to regard as a distinct species on the supposition of its being a probable hybrid between A. spinulosum (intermedium) and A. cristatum, but if it is to be considered only as a variety, then it comes nearer to cristatum than it does to spinulosum. So far as my own and the observations of my friends extend, whenever it varies at all it recedes toward cristatum. ”

“ An opinion prevails with many botanists that the large series of forms in this protean species so run into each other, and are oftentimes so confusing and difficult to place, that it would be better to ignore all of the so-called varieties and only recognize all forms under the one specific name. ”

“ But I will not undertake to decide this question here, the only object of the present paper being to give the results of my recent examinations, and to show, first, that we have good typical specimens of A. Spinulosum in abundance, and second, that the var. intermedium possesses sufficiently good distinctive characters to justify our regarding it as a good variety, if not a species. ”

“ DURING several seasons past I have been making some special examinations of the different forms of Aspidium spinuloslum as found growing in Middlesex county, Mass., and offer the result not as being decisive in character, but for the purpose of calling attention to the points involved, and inviting further investigations in the same direction. ”

“ This is too unreliable to be considered in any other way than in connection with the whole series of characters. The darker scales with blackish centers are found only on large and vigorous specimens of the var. inlermedium and, but more rarely in this vicinity, var. dilatalum, but both of these forms frequently have pale brown scales like those on spinulosum.
5. As to the character of the indusium. In spinulosum the indusia and under surface of the fronds are perfectly smooth, but in intermedium they are more or less glandular. ”

“ On the other hand the more northern form, peculiar to the mountainous regions of New Hampshire and Vermont, is so different in appearance, being in every way larger and more compound, that it may be desirable to have some way of designating it, even though the characters are of secondary importance. ”

“ What then is Aspidium spinulosum Swz.? Swartz says of it, "Frondibus bipinnatis, pinnis pinnatifidis pinnatisque, laciniis oblongis acutis serrato-spinulosis, fronde ovato-triangularis; rachis glabra. stipite paleaceo." "Addenda et emendata," p. 419 to Synopsis Filicum, 1806. This describes in part nearly all of our American forms. Let us analyze the description and see:
1. Fronds twice-pinnate. This is true in many cases of spinulosum, and the varieties dilatatum and intermedium. ”