The scientific classification of Rhubarb and Protea includes the entire classification chart that includes kingdom, family, clade, tribe etc. A kingdom is the second highest taxonomic rank. A taxonomic rank is the level that a living organisms are placed in hierarchical level of arrangement of life forms. All the living organisms are divided into kingdoms. Plant kingdom is a main classification of living organisms that include all plants. There are six kingdoms which are: Plantae, Animalia, Fungi, Protista, Aschaea/Archaeabacteria and Bacteria Eubacteria. Rhubarb and Protea kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Rhubarb and Protea family is a major factor of Rhubarb and Protea Scientific Classification. Plant family helps you narrow the search of your plants. It also gives you idea about, how the plant looks, how the seed will be like etc. These two plant families can be different or same. Rhubarb belongs to the family Polygonaceae and Protea belongs to the family Proteaceae.
While comparing scientific classification, Rhubarb and Protea genus and other classification are also important. Also, when you compare Rhubarb and Protea, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Rheum and other plant's genus is Protea. Rhubarb tribe is Not Available and Protea tribe is Proteae. Rhubarb clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales whereas Protea clade is Angiosperms and Eudicots and order is Proteales. Every plant have subfamilies. Rhubarb subfamilies are, Not Available and Protea subfamilies are Proteoideae. In this way you can compare scientific classification of Rhubarb and Protea and other products also.