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