The scientific classification of Rhubarb and Red Onion 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 Red Onion kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Rhubarb and Red Onion family is a major factor of Rhubarb and Red Onion 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 Red Onion belongs to the family Liliaceae.
While comparing scientific classification, Rhubarb and Red Onion genus and other classification are also important. Also, when you compare Rhubarb and Red Onion, 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 Allium. Rhubarb tribe is Not Available and Red Onion tribe is Not Available. Rhubarb clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales whereas Red Onion clade is Angiosperms and Monocots and order is Liliales. Every plant have subfamilies. Rhubarb subfamilies are, Not Available and Red Onion subfamilies are Allioideae. In this way you can compare scientific classification of Rhubarb and Red Onion and other products also.