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