BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

IV. PLANT ANATOMY AND MORPHOLOGY

Levels of Organization of Living Matter

Organisms, which represent highly complex polymolecular conglomerates, are classified into the following life forms:

Acellular, or pre-cellular, life forms: Viruses, Bacteriophages, Prions, Viroids;

Cellular life forms, which are subdivided into PROKARYOTES AND EUKARYOTES. Prokaryotes include unicellular forms (Bacteria), as well as colonial and multicellular forms (cyanobacteria). Eukaryotes encompass unicellular, colonial, non-cellular, and multicellular forms. The latter are further divided into thalloid and organ-based (leafy) forms—cormophytes.

Prokaryotes are organisms that lack a distinct membrane-bound Nucleus and intracellular membranous structures.

Eukaryotes are plant organisms possessing a membrane-bound nucleus and intracellular membrane structures—Organelles.

Unicellular plants consist of a single Cell that performs all the Functions of the Organism, such as reproduction, Nutrition, growth, etc. (e.g., Chlorella, Chlamydomonas).

Colonial organisms are groups of interconnected Cells formed through Vegetative Reproduction—by division or budding of a mother cell (found in certain cyanobacteria, diatoms, green and red Algae).

Non-cellular organisms are thalloid forms whose thallus is a single multinucleated cell not partitioned by cross-walls into individual cells. These include siphonous green and yellow-green algae, chytridiomycetes, oomycetes, and zygomycetes.

Multicellular thalloid organisms, or thallophytes, are Multicellular Organisms whose bodies are not differentiated into true Organs and Tissues (green, brown, and red algae, ascomycetes, Basidiomycetes, deuteromycetes, Lichens).

Multicellular leafy, or organ-based, plants—cormophytes—have a multicellular body differentiated into true organs and tissues (higher plants).