File:Contributions from the Botanical Laboratory, vol. 12 (1934) (20500469890).jpg

Title: Contributions from the Botanical Laboratory, vol. 12
Identifier: contributionsfro12univ (find matches)
Year: 1934 (1930s)
Authors: University of Pennsylvania. Botanical Laboratory; University of Pennsylvania. Morris Arboretum
Subjects: Botany; Botany
Publisher: Philadelphia : (s. n. )
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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Text Appearing Before Image:
. , = .,..;- â â â - ,t â â -i.^ J^i- American Fern Journal Volume 24, Plate 6 Fern Field Notes, 1934 103 Fig. 1. () ) ' i
Text Appearing After Image:
It* -^m^ Fig. 2. Fig. 3. Eastern Colonies of Woodsia scopulina: 1, in Ontario; 2, in Arkansas; 3, in North Carolina. accompanied by Dr. Horace G. Richards of Philadelphia, who is engaged in research work on Pleistocene problems. As has been pointed out by Professor M. L. Fernald,^ the isolated stations of Cordilleran plants now known to exist in northeastern North America are frequently located in areas which appear to have escaped glaciation by the last (Wisconsin) ice sheet, and a study of the locality in question from this standpoint, seemed desir- able. The fern was found to grow on a west-facing cliff of granite-gneiss about 50 feet up from the water-level of a small lake, tributary to Cache Lake. Scarcely fifteen living plants could be seen there, although there were remnants of a number of dead ones, indicating that* the colony is dwindling if not dying out. Professor Morris stated that it was indeed much larger at the time he first discovered it, but that a diminution in summer rainfall, erosion of material from the cliff, and encroachment by the forest have all combined to reduce its size. Care was accordingly taken to collect only a limited number of fronds, a few from each clump, so that its shrinkage would not be accelerated. A photograph of this colony is here reproduced as Plate 6, fig. 1. Unfortunately, no definite evidence bearing on the glacial history of the locality could be obtained. The slight extent of the weathering shown by the granite- gneiss outcrops and by the till which occurs at lower lev- els in the vicinity certainly suggested relatively recent glaciation. We were therefore inclined to favor the view that, as in the case of isolated stations for certain plants on Isle Royale, Lake Superior, the region was devegetated by Wisconsin ice, and the Woodsia has come in subsequently. However, more field work will be necessary before the matter can be regarded as settled. Last year an unsuccessful attempt had been made to 8 Mem. Amer. Acad. Arts Sci. 15: 241. 1925.

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