| Betula neoalaskana Sarg. | |
| Publ. & Syn. | Betula papyrifera subsp. humilis auct., non (Regel) E. Murray (1982). See notes. |
| Notes | The name Betula papyrifera subsp. humilis (Regel) E. Murray, Kalmia 12: 18 (1982) [Betula alba var. humilis Regel in DC., Prodr. 16, 2: 166 (1868)], has been applied for the main American Beringian tree-forming birch (e.g., Hultén 1968a). The synonymy between the Beringian Betula neoalaskana and the non-Beringian "humilis" needs confirmation. Variety humilis was described from Canada and U.S.A.: Saskatchewan (leg. Bourgeau), Rocky Mountains (leg. Parry, E. Hall, and P. Harbour), and White Mountains New Hampshire (leg. Tuckerman). About Betula "occidentalis". - Hultén (1968a, 1968b) applied the name Betula occidentalis Hook. for an Alaskan and Yukon taxon but suggested that it could be a hybrid. Furlow (1997) considered B. occidentalis Hook., Fl. Bor.-Amer. 2: 155 (1838), to be a non-arctic Cordilleran species. Dugle (1966) found no indication of a hybrid origin of this more southern B. occidentalis. Furlow (1997) therefore doubted Hultén's (1968a, 1968b) hypothesis of a B. occidentalis of hybrid origin in Alaska and the Yukon Territory, and he suggested B. occidentalis Hook. to be a derivative from the polyploid B. papyrifera. The Alaskan B. "occidentalis" is reported to be diploid (2n = 28, Woodworth 1930). A second report of 2n = 28 (2x) under the name Betula occidentalis is from Manitoba (Löve and Löve 1982a), well outside the range of B. occidentalis in both meanings of that name, and should be discounted. The assemblage of birches in the central and northern parts of Alaska and the Yukon Territory is fairly simple with two shrubs - B. nana and B. glandulosa - one tree - B. neoalaskana - and something in between: B. "occidentalis" which rather seems to be a variable hybrid swarm between B. neoalaskana (Hultén's B. papyrifera subsp. humilis) and B. glandulosa. It at least occasionally occurs well outside the range of one of its parents (B. neoalaskana) and is seed reproducing. Our field experiences in Alaska do, however, not support an independent taxon. |
| Chromosomes | 28 (2x). - Brittain and Grant (1969, several counts). Not included: A report of 2n = 28 (2x) under this name from Manitoba (Löve and Löve 1982a) is from outside the accepted range of the species. |
| Geography | American Beringian: ALA CAN. |
| Distribution | N = F AN = r E = R CC = r AW = r [ key ] |
| Parent taxon | Betula L. |
| PAF ID | 610203 |