Current definitions of "plant"When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts. From smallest to largest in inclusiveness, these three groupings are:
Land plants, also known as Embryophyta or Metaphyta. As the narrowest of plant categories, this is further delineated below.
Green plants - also known as Viridiplantae, Viridiphyta or Chlorobionta - comprise the above Embryophytes, Charophyta (i.e., primitive stoneworts), and Chlorophyta (i.e., green algae such as sea lettuce). It is this clade which is mainly the subject of this article.
Archaeplastida - also known as Plantae sensu lato, Plastida or Primoplantae - comprises the green plants above, as well as Rhodophyta (red algae) and Glaucophyta (simple glaucophyte algae). As the broadest plant clade, this comprises most of the eukaryotes that eons ago acquired their chloroplasts directly by engulfing cyanobacteria.
Outside of formal scientific contexts, the term "plant" implies an association with certain traits, such as multicellularity, cellulose, and photosynthesis.[2][3] Many of the classification controversies involve organisms that are rarely encountered and are of minimal apparent economic significance, but are crucial in developing an understanding of the evolution of modern flora.
