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By: Sperry, John SType: ArticleIn: Journal of the Arnold ArboretumVolume: 63Series:Issue: 2Date: 1982Page Range: 173--185Publication Info: Cambridge, Mass Arnold Arboretum, Harvard University [etc.] 1919-Subjects:
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By: Zimmermann, Martin Huldrych, - Sperry, John SType: ArticleIn: Journal of the Arnold ArboretumVolume: 64Series:Issue: 4Date: 1983Page Range: 599--609Publication Info: Cambridge, Mass Arnold Arboretum, Harvard University [etc.] 1919-Subjects:
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By: Sperry, John SType: ArticleIn: American fern journalVolume: 73Series:Issue:Date: 1983Page Range: 65--72Publication Info: [Washington, etc.] American Fern SocietySubjects: