Protist both microbial eukaryotes and macroscopic organisms that do not fit into the other traditional kingdoms. In cladistic systems (classifications based on common ancestry), there are no equivalents to the taxa Protista or Protoctista, both terms referring to a paraphyletic group that spans the entire eukaryotic tree of life. In cladistic classification, the contents of Protista are distributed among various "supergroups" (SAR, such as protozoa and some algae, Archaeplastida, such as land plants and some algae, Excavata, which are a group of unicellular organisms, and Opisthokonta, such as animals and fungi, etc.). "Protista", <nowiki>"Protoctista"</nowiki> and "Protozoa" are considered obsolete. However, the
Plasmodium (life cycle) fusion of cells after division. The term plasmodium, introduced by Leon Cienkowski, usually refers to the feeding stage of slime molds; these are macroscopic myxomycetes. The multinucleate developmental stages of some intracellular parasites, namely Microsporidia (now in Fungi) and Myxosporidia (now in Cnidaria), former cnidosporans, are also sometimes called plasmodia. Similarly, in Rhizaria, the ameboid, multinucleate protoplasts of some Cercozoan algae, e.g. Chlorarachniophyta, are called plasmodia. These lack cell walls; the syncytia are created by cell fusion. Some plasmodiophorids and haplosporidians are other multinucleated rhizarians. Plasmodium (life cycle) A plasmodium is a living structure of cytoplasm that contains many nuclei,