Rubus tholiformis is a rare North American species of flowering plant in the rose family. It has been found only in eastern Canada (Québec and Nova Scotia) and the northeastern United States (Maine, New Hampshire, Vermont).Biota of North America Program 2014 county distribution mapMerritt Lyndon. 1940. Rhodora 42(500): 283–284 description in Latin, commentary in EnglishFernald, Merritt Lyndon. 1940. Rhodora 42(500): plates 606 + 607 photos of Rubus aculifer
The genetics of Rubus is extremely complex, so that it is difficult to decide on which groups should be recognized as species. There are many rare species with limited ranges such as this. Further study is suggested to clarify the taxonomy.Flora of North America, Rubus Linnaeus, 1754. Bramble Some studies have suggested that R. tholiformis may have originated as a hybrid between R. setosus and R. hispidus.Flora of North America, Rubus setosus Bigelow, 1824. Bristly blackberry, ronce sétuleuse
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