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Square-stalked St. John’s-wort, Hypericum tetrapterum, in Peel Region, Ontario: a New Non-native Vascular Plant Species for Eastern North America
- Cecile, Charles P., Oldham, Michael J.
- Canadian field-naturalist 2016 v.130 no.3 pp. 231-235
- Hypericum, Thuja occidentalis, coasts, swamps, British Columbia, Ontario, Washington (state)
- 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).