Lycopus americanus subsp. Laurentianus (Lamiaceae): An Eastern Canadian Endemic Taxon New to the United States

Abstract

ABSTRACT. A new status for Lycopus laurentianus is proposed: Lycopus americanus subsp. laurentianus, and the taxon is newly reported from the United States with occurrences in Maine, New Hampshire, New York, and Vermont. Six occurrences in Vermont and three in New York were discovered on the shores of Lake Champlain in 2007. Subsequent review of L. americanus specimens from herbaria yielded more occurrences of L. americanus subsp. laurentianus in New York and Vermont, as well as new occurrences in New Hampshire and in Maine. Important publications and data previously available only in French of this relatively obscure taxon are also presented. Nutlet morphology is presently the only reliable diagnostic character separating L. americanus subsp. laurentianus from L. americanus subsp. americanus.