Heterotrophic Plants

HETEROTROPHIC PLANTS (from Greek heteros - other, and trepho - I nourish), plants incapable of utilizing CO₂ as a source of carbon for building organic matter and therefore requiring nutrition from organic compounds. They are contrasted with autotrophic plants, which can build organic matter from inorganic and do not need organic nutrition. Heterotrophic plants include almost all chlorophyll-free plants: fungi, the majority of bacteria (with the exception of a few autotrophic ones, such as nitrifying bacteria and others), and a few flowering plants devoid of chlorophyll. Some heterotrophic plants live in nature as saprophytes, at the expense of dead organic matter, while others live as parasites, at the expense of another living organism: animal or plant. The former are frequently called metatrophs, and the latter paratrophs. Between them exist numerous transitions, and in many cases it is possible to grow parasitic plants in artificial culture under saprophytic conditions. Most essential for the nutrition of heterotrophic plants is the source from which they draw their carbon. This is always organic compounds, varying in different cases. For the vast majority, the best source of carbon is soluble sugars. Below sugars stand polyhydric alcohols and acids, with higher homologues exceeding lower ones in nutritional value, and compounds with an unbranched chain surpassing those with a branched carbon chain. Cyclic compounds are almost always a significantly poorer carbon source than fatty series compounds. Finally, for many heterotrophic plants, proteins and amino acids can serve as a carbon source, although sugars are usually considerably better in this regard. As for nitrogen nutrition, some heterotrophic plants, especially parasitic ones, require nitrogen in the form of proteins or amino acids; however, the vast majority readily assimilate NH₃ and nitric acid, and some even elemental nitrogen. In this character of nitrogen nutrition, heterotrophic plants differ from animals, which, as is well known, obligatorily require organic nitrogen (proteins and amino acids). Autotrophic (inorganic) nutrition with one element and heterotrophic (organic) nutrition with another is sometimes called mixotrophic nutrition. In this sense, the majority of heterotrophic plants are mixotrophic. More frequently, however, mixotrophic is used to designate mixed nutrition with a single element, especially carbon. The ability, alongside CO₂, to assimilate to a certain degree also organic carbon is likely characteristic without exception of all green plants in artificial settings; in some, however, which are poor in chlorophyll and therefore weakly assimilate CO₂, this ability to assimilate organic carbon has a predominant role in nutrition (dodder, broomrape, bird's-nest orchid, etc.). Mixotrophic nutrition is especially widespread among primitive green algae, even those containing normal amounts of chlorophyll. It is variously expressed in different forms and serves as a very important factor in their distribution in nature, while also allowing them to be utilized in biological water analysis (see). L. Karsinov. HETEROPHASIA, HETEROPHRAZIA, otherwise paraphasia, represents a speech disorder in which some words are used instead of others (verbal heterophasia) or some letters are replaced in a word by others (literal, or letter heterophasia). Heterophasia particularly characterizes the symptom complex of cortical and transcortical sensory aphasia, but is also encountered in transcortical motor aphasia. In sensory aphasia, speech due to severe heterophasia can become entirely incomprehensible, resembling a peculiar jargon (so-called jargonaphasia).