The scientific classification of Saguaro and Cleistocactus 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. Saguaro and Cleistocactus kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Saguaro and Cleistocactus family is a major factor of Saguaro and Cleistocactus 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. Saguaro belongs to the family Cactaceae and Cleistocactus belongs to the family Cactaceae.
While comparing scientific classification, Saguaro and Cleistocactus genus and other classification are also important. Also, when you compare Saguaro and Cleistocactus, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Carnegiea and other plant's genus is Cleistocactus. Saguaro tribe is Pachycereeae and Cleistocactus tribe is Trichocereeae. Saguaro clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales whereas Cleistocactus clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales. Every plant have subfamilies. Saguaro subfamilies are, Cactoideae and Cleistocactus subfamilies are Cactoideae. In this way you can compare scientific classification of Saguaro and Cleistocactus and other products also.