Carduus megacephalus (A.Gray) Nutt. Dataset GBIF Backbone Taxonomy Rank SPECIES Classification kingdom Plantae phylum Tracheophyta class Magnoliopsida order Asterales family Asteraceae genus Cirsium species Cirsium undulatum Name Homonyms Carduus megacephalus A.Nelson Carduus megacephalus (A.Gray) Nutt. ex Daniels, 1911 Carduus megacephalus A.Gray Carduus megacephalus Smyth, 1899 Carduus megacephalus (A.Gray) Nutt.