184 Rhodora [SEPTEMBER 
either long sori, rather sharply hooked at one end (hamate), or else 
long horse-shoe shaped, while the short and almost round type so 
commonly found in A. Filix-femina is very uncommon. Diplazioid 
sori are somewhat rare, but are more common than in A. Filix-femina 
(see Plate 123, figs. 4, 6, 11, 13 and 16, also text-figs. 3—5, pp. 175, 176).! 
The indusium of both American species is broadest at the base, 
and is often markedly decurrent along the subtending vein. The 
margin of the indusium of A. angustum is usually toothed, or furnished 
with a few short one-celled cilia (Plate 123, fig. 17). Rarely, espe- 
cially in the later fronds of the season, it has a few longer, multicellular 
cilia similar to those found in A. Filix-femina. The indusium of A. 
asplenioides is ciliate with multicellular hairs which have swollen 
glandular tips of a yellow-brown color, a character which is con- 
spicuous under the compound microscope in the recently matured 
indusium, but is sometimes difficult to demonstrate in over mature 
specimens, in which the cilia are often broken (Plate 123, fig. 8). 
The indusia of the largest sori in A. angustum measure on the average, 
0.5 mm. high, by 1.1 mm. long, those of A. asplenioides 0.45 mm. high, 
by 1.3 mm. long. . Even the small sori toward the tips of the pinnae 
never have indusia higher than they are long. 
In A. asplenioides the stalk of the sporangium bears a yellowish, 
long-stalked, glandular body (Plate 123, fig. 9). In A. angustum, 
similar glands are common but by no means as uniformly present as in 
A. asplenioides, and sometimes the stalks of the sporangia proliferate 
and bear secondary sporangia as in Filix-femina. 
The spores of A. angustum resemble those of A. Filix-femina; their 
average size is 38.6 X 24.7 u. The spores of A. asplenioides, on the 
other hand are furnished with a nigrescent, wrinkled or reticulate 
exospore, and resemble rather the spores of A. alpestre of arctic-alpine 
Europe and America. Their average size is 36.0 X 25.5 u (Plate 123, 
figs. 10 and 18). 
It will be seen, therefore, that the two species of lady ferns of the 
eastern states and Canada differ from each other and from A. Filiz- 
femina in characters of rootstock, scales, fronds, sori, indusia and spores. 
The history of the treatment of these ferns by botanists, American 
1 Asplenioid sori in the Amacican species, particularly the rather long ones of A. asplenioides, 
are somewhat curved, or ‘“‘lunate,” with the convex side facing away from the subtending vein. 
The amount of this curve depends chiefly on the absolute length of the sorus. It is not to be 
confused with the sharp bend which occurs in athyrioid sori. 
