THE FERNS OF HEMLOCK BLUFF. 147 



the Virginia end of the dam above the Great Falls Cheilanthcs lanosa 

 is abundant, while Dryopteris cristata and Dryopteris spinidosa occur 

 sparingly in rich woodland bottoms. Pelh-ea atropurpiirea has been 

 found at the Great Falls and Mr. Topping found it two years ago on 

 Plummer's Island. Elsewhere about Washington it grows on wells 

 and culverts. Several late visits have resulted in the discovery of 

 many more plants of Onoclea Striithiopteris scattered along several 

 miles of the bases of these bluffs, sometimes in the sandy mud but 

 more often on the low, rocky shelves, near the high water line. 

 BotrycJiiinn dissectiiui and B. obliqiium are not uncommon in low places 

 along these bluffs, but so far they have not been noticed on Hemlock 

 Bluff. Below Harper's Ferry I have found Cystopteris bulbifcra, 

 which no doubt will some day be found nearer Washington. 



On the afternoon of March 26, 1899, a party of us had landed 

 some two miles below Scott Run and had examined the cliffs and 

 shore line for some distance toward that stream. Many dead fronds 

 of Onoclea Striithiopteris were noticed, and also quite a number of 

 Camptosorus and the more common species. While examining the 

 face of the high, well-shaded portion of a cliff, I was surprised to dis- 

 cover in a narrow rift of the rock but a few feet in front of me, two 

 plants of Aspleniiun pinnatifidiim which had heretofore never been 

 found in this vicinity. This most unexpected find stimulated the 

 efforts of the party to such an extent that about ten minutes later Mr. 

 W. R. Maxon, while scaling the more exposed portion of the cliff, 

 discovered other plants, and a few minutes later every member of 

 the party found as many plants as were desired and left many others. 

 The specimens just found were large and deeply colored, owing to 

 their shady, moist situation, while the others had paler and smaller 

 fronds. The fronds of the former have short stipes while those of 

 the latter, owing to the deepness of the cracks in which they were 

 growing, have long stipes and shorter fronds. 



Though many cliffs have been examined no other plants of this 

 fern have been found. The cause of its presence on this particular 

 cliff is undoubtedly due to the presence of sufficient root moisture to 

 counteract the drying powers of the wind. The crevices are long, 

 narrow and vertical, thus differing from the generally horizontal 

 fractures common on the other cliffs. Most of the plants were deep 

 in the recesses of the narrow cracks where their roots especially were 

 well protected. This slope exposure is sufficient to account not only 

 for the presence of this fern, but of many others on these bluffs. 

 Cutting off the trees would result in their utter extermination. Of 

 the thirty-eight species of ferns now known from the vicinity of 

 Washington, but four are not known to occur about these bluffs, the 

 two Woodwardias, Ophioglossiivi vtilgatiiin, and Lygodiiim palmatinn. 



