The scientific classification of Old Man Cactus and Devil's Tongue 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 Devil's Tongue kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Old Man Cactus and Devil's Tongue family is a major factor of Old Man Cactus and Devil's Tongue 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 Devil's Tongue belongs to the family Araceae.
While comparing scientific classification, Old Man Cactus and Devil's Tongue genus and other classification are also important. Also, when you compare Old Man Cactus and Devil's Tongue, 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 Amorphophallus. Old Man Cactus tribe is Pachycereeae and Devil's Tongue tribe is Thomsonieae. Old Man Cactus clade is Angiosperms, Core eudicots and Eudicots and order is Caryophyllales whereas Devil's Tongue clade is Angiosperms and Monocots and order is Alismatales. Every plant have subfamilies. Old Man Cactus subfamilies are, Cactoideae and Devil's Tongue subfamilies are Aroideae. In this way you can compare scientific classification of Old Man Cactus and Devil's Tongue and other products also.