The scientific classification of Pepperwort and Crown-of-Thorns 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. Pepperwort and Crown-of-Thorns kingdom and all other plants kingdom is Plantaea.
Plant family is the group of plants which have something in common. Pepperwort and Crown-of-Thorns family is a major factor of Pepperwort and Crown-of-Thorns 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. Pepperwort belongs to the family Marsileaceae and Crown-of-Thorns belongs to the family Euphorbiaceae.
While comparing scientific classification, Pepperwort and Crown-of-Thorns genus and other classification are also important. Also, when you compare Pepperwort and Crown-of-Thorns, other factors should also be taken into considerations like order, subfamilies, tribe, clade etc. First plant's genus is Marsilea and other plant's genus is Euphorbia. Pepperwort tribe is Lapidieae and Crown-of-Thorns tribe is Euphorbieae. Pepperwort clade is Angiosperms, Eudicots and Rosids and order is NA whereas Crown-of-Thorns clade is Angiosperms, Eudicots and Rosids and order is Euphorbiales. Every plant have subfamilies. Pepperwort subfamilies are, NA and Crown-of-Thorns subfamilies are Euphorbioideae. In this way you can compare scientific classification of Pepperwort and Crown-of-Thorns and other products also.