— 10 — 



turn, leaving what looks like a diplazioid or double sorus, with 

 two parts lying back to back. In thelypteroides, on the con. 

 trary, the pinnae and pinnules are narrow and the sori straight, 

 parallel and set close together, so close that there is no room to 

 cross the veinlet and run down the other side, although toward 

 the tips of the pinnae the sori are often double, or diplazioid. 



My arrangement of these would be as follows: Asplenium 

 acrostichoides Sw. Pinnae and pinnules broad, sori on lower 

 pinnae often athyrioid. Asplenium acrostichoides thelypteroides 

 Michx. Pinnae and pinnules narrow, sori straight, parallel, set 

 closely together. 



If collectors who have the two forms in their herbaria will 

 compare them together, they will find the difference quite striking, 

 enough so, it seems to me, to form a valid variety. 



Swartz gives the range of acrostichoides as North America 

 in general; but he confines thelypteroides to the mountains of 

 Virginia and North Carolina, which is probably the range given 

 by Michaux. According to my own observation, A. a. thelypte- 

 roides is much more common in central New York than A. acrosti- 

 choides, which may be called rather scarce than otherwise. I 

 should be glad to hear of the comparative range of the two from 

 other parts of the north. 



In connection with a fern which I gathered last fall, I want 

 to say a few words about Dryopteris dilatata. Babington, Sow- 

 erby, Smith, Moore, Hoffmann, Presl, DeCandolle, and most of 

 the older botanists, regarded this' as a distinct species. But all 

 of them, whether they considered it a species or a variety, char- 

 acterized it as having an "indusium fringed with stalked glands." 

 American botanists, however, from an early period, made the 

 point that the indusium was "smooth and naked," and this has 

 been insisted upon as an indispensable requisite of the variety in 

 this country. But is it so ? If it has indusia with stalked glands 

 in Europe, why may it not have them in this country also ? It 

 seems to me that the distinction is false, and cannot be regarded 

 as imperative. The mere fact that much of the dilatata found 

 here has a naked indusium does not preclude the possibility of a 

 form that may agree with the English form. The fronds of which 

 I have already spoken have indusia with stalked glands ; hence 

 they cannot be spinulosa proper. On the other hand, their gen- 

 eral form and cutting are quite unlike the var. intermedia, while 

 they are very like the English form of Lastrcea dilatata glandu- 



