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