Rheum undulatum var. rotundifolium Metzg. Dataset GBIF Backbone Taxonomy Rank VARIETY Classification kingdom Plantae phylum Tracheophyta class Magnoliopsida order Caryophyllales family Polygonaceae genus Rheum species Rheum rhabarbarum Name Homonyms Rheum undulatum var. rotundifolium Metzg. ex Alef. Rheum undulatum var. rotundifolium Metzg.