7301 Diapensia L.
- L., Sp. Pl.: 141 (1753).
Notes: Two taxa are generally accepted in the Arctic and variously treated as races or species: Diapensia lapponica and D. obovata (D. lapponica var./subsp. obovata). The former is broadly amphi-Atlantic and the latter broadly amphi-Pacific with a small gap in northern Siberia but perhaps with a slight overlap in northwestern Canada (however, Nesom 2009 stated the gap in Canada to be about 1000 km). They are largely non-overlapping morphologically but some fertile intermediates have been reported and vouchered (CAN, DAO) from the Mackenzie and Richardson mountains west of the Mackenzie River (included in D. obovata by Nesom 2009). Yurtsev (PAF proposal) accepted two species based on the near full allopatry and several differential, mainly quantitative characters: growth form (pulvinate in D. lapponica vs. prostrate and mat-forming in D. obovata), and differences in shape and colour (green vs. lilac green) in leaves, bracteoles and sepals. Nesom (2009) specified more characters and discussed why he chose specific rank.
Yurtsev argued that D. obovata is closer to Himalayan species (where the three other accepted species of the genus occur, see Scott and Day 1983) and might have its affinity to a different series or section. Aiken, Murray, and Elven argued that the rank of subspecies is more suitable with the described geographical and morphological pattern. Both solutions are appropriate but acceptance as two species has been chosen due to the arguments of Yurtsev and Nesom.
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Source: Indolences at Wikispecies
Higher Taxa
- Diapensiaceae [73,family]