Wintercresses (Barbarea W.T. Aiton, Brassicaceae) of the Canadian Maritimes

Résumé

We conducted a review of herbarium collections of the Wintercress genus (Barbarea W.T. Aiton) from the Maritime provinces. Most specimens previously determined to be the regionally rare native species Erect-fruit Wintercress (Barbarea orthoceras Ledebour) are in fact the uncommon exotic Small-flowered Wintercress (Barbarea stricta Andrzejowski). The latter species is here reported as new to Atlantic Canada, where it is scattered but widespread in the three Maritime provinces. Only three collections (two from New Brunswick and one from Nova Scotia) were confirmed as B. orthoceras. Its known range extent and area of occupancy in the Maritimes has been significantly revised, and B. orthoceras is now considered potentially extirpated in New Brunswick and extremely rare in Nova Scotia. One collection from Nova Scotia was referred to another rare exotic species, Early Wintercress (Barbarea verna (Miller) Ascherson), which represents the first record for the Maritimes.