274 * ^ Rhodora [NOVEMBER 
ADDITIONAL NOTES ON BOTRYCHIUM TENEBROSUM. 
A. A. EATON. 
(Plate 48.) 
DURING the past season I have made a few additional observations 
on Botrychium tenebrosum, A. A. Eaton, and in making them public it 
seems advisable to incorporate them in a general description for the 
readers of RHODORA, so that they may familiarize themselves with 
this quite common but little known New England plant. 
Botrychium tenebrosum (Plate 48) is a species found only in rich 
humus or leaf-mould, in deep moist shade. It is usually quite small, 
often thread-like, and fruiting even when covered by leaves, but some- 
times growing to a height of g inches. Usually the plants are 3 to 4 
inches high. ‘They are yellowish green, very glabrous and shining 
when young, decumbent and stramineous when older, becoming thin 
and transparent when pressed. The sterile laminae are near the 
fertile, often overtopping them (Fig. 3). They are always simple 
with 2 to 8 distant, lunate, rarely incised lobes, the terminal usually 
retuse (Figs. 8, 9). The lobes are apparently never spread out 
flat, but are in the same position which they have in bud. "The 
fertile lamina is usually simple, the large sporangia being sunk in 
the tissues of the broadened rachis. When the frond is compound, 
the ultimate segments are similar to the fruited segments of the 
sterile lamina, the rachis broad and leaf-like (Fig. 5). 
It is apparently a northern species, being quite rare about North 
Easton and Brockton, Massachusetts, the southernmost point from 
which I have it. In southern New Hampshire and northern Massa- 
chusetts it usually is found in wet maple swamps, often in or around 
the depressions near sluggish streams in which leaves accumulate 
and decay. My first plants were growing in sphagnum. The sparse 
vegetation is often of Onoclea sensibilis and Rhus Toxicodendron, and 
it is often accompanied by B. matricariacfolium and B. lanceolatum, 
and even varieties of B. /eruatum. In Maine, however, it appears 
to affect the mounds of humus in cedar swamps, farther from water. 
As found in Madison, Maine, on July 2d last, it appeared to be 
more at home than farther south, as the plants were better developed 
and characteristic in appearance. It was also found to become 
