The subfamily Dryadoideae consists of four genera in the family
Rosaceae,
[.] all of which contain representative species with
root nodules that host the
nitrogen-fixing
Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atm ...
bacterium
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were amon ...
''
Frankia
''Frankia'' is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the ''Rhizobium'' bacteria found in the root nodules of legumes in the family Fabaceae. ''Frankia'' also initiate the forming of root ...
''. They are subshrubs, shrubs, or small trees with a
base chromosome number of 9, whose fruits are either an
achene or an
aggregate of achenes.
[
]
Taxonomic history
The subfamily has at various times been separated as its own family (Dryadaceae), or as a tribe (Dryadeae) or subtribe (Dryadinae).
References
External links
*
*
Rosid subfamilies
{{rosaceae-stub