 ==subgenus betulenta - wintergreen oil birches== bark on twigs rich in methyl salicylate (oil of wintergreen). female catkins erect. *diploid (2n = 28). **betula lenta - sweet birch or cherry birch ***betula lenta subsp. uber - cherry creek birch *hexaploid (6n = 84). **betula allegheniensis - yellow birch (b. lutea) *decaploid (10n = 140). **betula austrosinensis - south china birch **betula globispica - **betula insignis - **betula medwediewii - caucasian birch *duodecaploid (12n = 168). **betula megrelica - *chromosome number not reported **betula corylifolia - hazel-leaf birch **betula grossa - japanese cherry birch **betula insignis - ==subgenus betulaster - large-leaf birches== bark on twigs contains some methyl salicylate. female catkins pendulous. **betula alnoides - alder-leaf birch ***betula alnoides subsp. luminifera - **betula maximowiczii - monarch birch ==subgenus neurobetula - costate birches== bark on twigs without methyl salicylate. female catkins erect. *diploid (2n = 28). **betula calcicola - **betula chichibuenis - **betula costata - **betula nigra - river birch or black birch **betula potaninii - potanin's birch *tetraploid (4n = 56). **betula albosinensis - chinese red birch ***betula albosinensis var. septentrionalis - north chinese red birch **betula ermanii - erman's birch **betula jacquemontii (b. utilis subsp. jacquemontii) - white-barked himalayan birch **betula utilis - himalayan birch *hexaploid (6n = 84). **betula dahurica - dahurian birch **betula delavayi - delavay's birch **betula raddeana - radde's birch *octoploid (8n = 112). **betula chinensis - chinese birch *chromosome number not reported **betula fargesii - farges's birch **betula schmidtii - schmidt's birch *chromosome number unknown **betula leopoldae &  1987. middle eocene dicotyledonous plants from republic, northeastern washington. united states geological survey bulletin 1597:13  &  1987; "betula leaves and reproductive structures from the middle eocene of british columbia, canada." canadian journal of botany 65(12): 2490-2500. ==subgenus betula - typical birches== bark on twigs without methyl salicylate. female catkins pendulous. *diploid (2n = 28). **betula cordifolia - heart-leaf birch or mountain paper birch **betula pendula - silver birch **betula mandschurica - manchurian birch ***betula mandschurica var. japonica 
Betula