640502-04 The Rubus arcticus aggregate R. acaulis, R. arcticus, R. stellatus
Geography: Nearly circumboreal-polar.
Notes: Rubus arcticus s. lat. has been accepted either as a polymorphic species with three geographically overlapping (parapatric) races, all reaching the Arctic, or as three species. Both viewpoints can be justified. The three taxa are the mainly Eurasian R. arcticus s. str., the amphi-Pacific R. stellatus (or subsp. stellatus), and the mainly or entirely North American R. acaulis (or subsp. acaulis). The morphological differences are found in several parts of the plants and they are not of an adaptive kind. However, the plants are interfertile and intermediates are frequent where their ranges overlap. The pattern can be interpreted as resulting from gradual divergence in isolation followed by secondary (post-Pleistocene) contact. Porsild and Cody (1980) and some other North Americans accept specific rank. Hultén (1946) at first did the same but later (Hultén 1968a, 1968b; Hultén and Fries 1986) went for three subspecies and argued that hybrid swarms are formed where they overlap. Gladkova (PAF proposal) accepted species. We follow her proposal as we find the differences among the three taxa pronounced and not compromised by the intermediates.
Higher Taxa
- Rubus [6405,genus]