1917] Butters,— Studies in Ferns — Botrychium 209 
tianum, var. nov., fronde sterili crassiore, segmentis ordinum omnium 
latioribus rebus formae typicae iisdem, segmentis confertis imbricatis 
ultimis spathulatis, fronde fertili crassa conferte paniculata segmentis 
ultimis herbaceis complanatis 0.5~-1.0 mm. latis, sporangiis flavis 1-1.8 
mm. longis (exsiccatis) anguste apertis. 
This variety is characterized by its thick and heavy sterile frond, 
less finely divided than in the typical form, and with the segments so 
crowded that they overlap one another. Though it is generally smaller 
than the typical Botrychium virginianum, it occasionally reaches 
large size, the largest specimen seen, having the sterile frond 18 cm. 
long and 28 cm. wide. The pinnules are shorter than in typical 
Botrychium virginianum, and tend to be ovate in form and the ulti- 
mate segments are strongly spatulate. The fertile spike is relatively 
short and stout, and in well developed specimens is very strongly 
paniculate. Its ultimate segments are flat, foliaceous, and often 1 mm. 
wide. 
It is, however, in the sporangia that this form differs most greatly 
from Botrychium virginianum. Indeed these organs resemble rather 
those of Botrychiwm Lunaria than those of typical Botrychium vir- 
ginianum. They are 1-1.8 mm. long when dried, and sometimes 
exceed 2 mm. when fresh. When ripe, they are of a dark straw color 
like those of Botrychiwm Lunaria. Before dehiscence the line of 
fracture shows as a distinct paler band. In dehiscence they open but 
slightly, and the valves never become recurved. When moistened, 
they close again, regaining their almost spherical form (see fig. 6, 
p. 208 D and E). Under the microscope the walls of the sporangia 
appear very translucent, and the cells of the outer layer are seen 
to be of regular quadrilateral or polygonal form with nearly straight 
thickened walls (see fig. 6, p. 208, F). 
So different is this fern from typical Botrychium virginianum, that, 
were it not for the intermediate varieties discussed below, it would 
certainly take rank as a distinct species. It grows typically in open, 
grassy places, occasionally on exposed rocks or talus. It is almost 
confined to the calcareous districts in the vicinity of the Gulf of St. 
Lawrence, as is shown by the following list of the specimens in the 
Gray Herbarium. 
LABRADOR: lim and caleareous sandstone terraces, Blanc 
eg Straits of Belle Tale, August 6, 1910, Fernald and Wiegand 
