Subgenera of genus Betula (birch), are;

Subgenus Betulenta - Wintergreen oil birches

Bark on twigs rich in methyl salicylate (oil of wintergreen). Female catkins erect.

Subgenus Betulaster - Large-leaf birches

Bark on twigs contains some methyl salicylate. Female catkins pendulous.

Subgenus Neurobetula - Costate birches

Bark on twigs without methyl salicylate. Female catkins erect.

Subgenus Betula - Typical birches

Bark on twigs without methyl salicylate. Female catkins pendulous.

Subgenus Chamaebetula - Dwarf birches

Small shrubs with small rounded leaves. Female catkins pendulous.

Notes

There is no consensus at all on species limits in Betula, with different authors differing wildly in what species they accept, from under 30 species, to over 60. The above (incomplete) list was compiled from the references cited below. Birches will hybridise very freely, particularly in cultivation but also in the wild where conditions and species present permit. While differing chromosome number (diploid, tetraploid, etc.) may reduce interbreeding, it is not an absolute bar to it. Many botanists regard differing chromosome number as a specific discriminant, though not all do so (e.g. some include B. cordifolia and B. neoalaskana as varieties within B. papyrifera).

References

  1. ^ English Names for Korean Native Plants (PDF). Pocheon: Korea National Arboretum. 2015. p. 373. ISBN 978-89-97450-98-5. Archived from the original (PDF) on 25 May 2017. Retrieved 16 December 2016 – via Korea Forest Service.
  2. ^ Wolfe, Jack A. & Wehr, Wesley C. 1987. Middle Eocene Dicotyledonous Plants from Republic, Northeastern Washington. United States Geological Survey Bulletin 1597:13
  3. ^ Crane P.R. & Stockey R.A. 1987; "Betula leaves and reproductive structures from the Middle Eocene of British Columbia, Canada." Canadian Journal of Botany 65(12): 2490-2500.

See also

Categories