The Plant List contains a working list of plants of the world. The species included are grouped into $psd.totalGenera genera, $psd.totalFamilies families and 4 major groups.
Use the Browse function to explore the taxonomic hierarchy embedded within The Plant List. You can work down the taxonomic hierarchy from Major Group (to find out which Families belong to each), to Family (to work out which Genera belong to each) or Genus (to find out which Species belong to each).
From within the taxonomic hierarchy you will be able to move upwards so as to discover, for example, to which Family a particular Genus belongs.
You can also browse genera found in The Plant List.