Square-stalked St. John’s-wort, Hypericum tetrapterum, in Peel Region, Ontario: a New Non-native Vascular Plant Species for Eastern North America

Charles P Cecile, Michael J Oldham


The Eurasian Square-stalked St. John’s-wort (Hypericum tetrapterum Fr.: Hypericaceae) was found growing in an open Eastern White Cedar (Thuja occidentalis L.) swamp in Caledon, Regional Municipality of Peel, Ontario. This is the first record for eastern North America; previous North American occurrences have been on the Pacific coast in Vancouver, British Columbia, Canada (1991), and in Wahkiakum County, Washington State, USA (2003).


Hypericum tetrapterum; Square-stalked St. John’s-wort; Hypericaceae; vascular plant; Peel Region; Ontario; Canada; new record; non-native

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DOI: http://dx.doi.org/10.22621/cfn.v130i3.1886

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