. Contributions from the Botanical Laboratory, vol. 11. Botany; Botany. Type specimen collected in dry woods on *'Top of the rid^e behind Rattlesnake Den, Sweet Sprinp^s/' Monroe County, West Virginia, by . Frederick Pursh in 1806, in herbarium Academy Natural Sciences, Philadelphia. The ran^e of this Convolvulus hitherto reported is from Alleghany County, Virginia, to Allegany County, Maryland. In June, 1920, it was collected at Charter Oak, Huntingdon Co., Pa., by W. C. Muenscher, but distributed to herbaria as C. spithamaeus. Search for it in 1932 resulted in finding it at several places in
. Contributions from the Botanical Laboratory, vol. 11. Botany; Botany. Type specimen collected in dry woods on *'Top of the rid^e behind Rattlesnake Den, Sweet Sprinp^s/' Monroe County, West Virginia, by . Frederick Pursh in 1806, in herbarium Academy Natural Sciences, Philadelphia. The ran^e of this Convolvulus hitherto reported is from Alleghany County, Virginia, to Allegany County, Maryland. In June, 1920, it was collected at Charter Oak, Huntingdon Co., Pa., by W. C. Muenscher, but distributed to herbaria as C. spithamaeus. Search for it in 1932 resulted in finding it at several places in Bedford, Fidton, and Huntingdon Counties, Pennsylvania, on slopes of Devonian shale. Senecio antennariifolius Britton The occurrence of this plant in Pennsylvania has already been re- corded by State Botanist Gress,^ and no new stations for it have been dis- covered. This plant shows a different geographic relation than the other species here included: instead of being related, like these, to plants which approach or enter the Appalachians, its nearest relative occurs in the Rocky Mountains, two thousand miles away. The only reasonable ex-. FiG. 20. Map of the ranges of Senecio canus and S. antennariifolius as known up to April, 1933, bringing out their interpretation as the only surviving descendants of an ancestor which lived in the Hudson Bay region during pre-Glacial time. planation of such a distribution is that during Tertiary times the an- cestor of both species grew somewhere in what is now central Canada, and descendants chanced to migrate out far enough to escape destruction by the Quaternary ice sheets in two regions. Since the ice retreated the western species has been able to regain some of the lost territory, but the eastern one, having seemingly become more conservative, has not yet returned even as far as the Wisconsin terminal moraine. *Proc. Penna. Acad. Sciences 4: 29. Please note that these images are extracted from scanned page images that may have
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