Myxomycetes: A division of organisms that exist vegetatively as complex mobile plasmodia, reproduce by means of spores, and have complex life cycles. They are now classed as protozoa but formerly were considered fungi.Physarum: A genus of protozoa, formerly also considered a fungus. Characteristics include the presence of violet to brown spores.Spores, Protozoan: A vegetative stage in the life cycle of sporozoan protozoa. It is characteristic of members of the phyla APICOMPLEXA and MICROSPORIDIA.Physarida: An order of protozoa characterized by a peridium and capillitium that are calcareous and a spore mass that is usually dark-colored.Asclepias: A plant genus of the family ASCLEPIADACEAE. This is the true milkweed; APOCYNUM & EUPHORBIA hirta are rarely called milkweed. Asclepias asthmatica has been changed to TYLOPHORA.Yucca: A genus (and common name) in the AGAVACEAE family. It is known for SAPONINS in the root that are used in SOAPS.Plant Bark: The outer layer of the woody parts of plants.Desert Climate: A type of climate characterized by insufficient moisture to support appreciable plant life. It is a climate of extreme aridity, usually of extreme heat, and of negligible rainfall. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Physarum polycephalum: A protozoan, previously also considered a fungus. Characteristics include sporangia that are stalked and multilobed. It is widely used in biomedical research.Caesalpinia: A plant genus of the family FABACEAE. The common name of "Bird-Of-Paradise" is also used for other plants such as Heliconia (HELICONIACEAE) and Strelitzia (STRELITZIACEAE) and some birds. The common name of "Cat's-Claw" is more often used with UNCARIA. The common name of "Pernambuco" also refers to a state in Brazil. Furanoditerpenoid lactones and caesalpin are produced by members of this genus.Agavaceae: A plant family of the order Liliales, subclass Liliidae, class Liliopsida. Members of the family have narrow, lance-shaped, sometimes fleshy or toothed leaves that are clustered at the base of each plant. Most species have large flower clusters containing many flowers. The fruit is a capsule or berry.Echinacea: A genus of perennial herbs used topically and internally. It contains echinacoside, GLYCOSIDES; INULIN; isobutyl amides, resin, and SESQUITERPENES.Snow: Frozen water crystals that fall from the ATMOSPHERE.Ribosome Subunits, Small: The small ribonucleoprotein component of RIBOSOMES. It contains the MESSENGER RNA binding site and two TRANSFER RNA binding sites - one for the incoming AMINO ACYL TRNA (A site) and the other (P site) for the peptidyl tRNA carrying the elongating peptide chain.Isatis: A plant genus of the family BRASSICACEAE that is an ingredient of the preparation PC-SPES that is used to treat PROSTATIC HYPERPLASIA.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.ChileWood: A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.Pinus: A plant genus in the family PINACEAE, order Pinales, class Pinopsida, division Coniferophyta. They are evergreen trees mainly in temperate climates.Microscopy, Electron, Scanning: Microscopy in which the object is examined directly by an electron beam scanning the specimen point-by-point. The image is constructed by detecting the products of specimen interactions that are projected above the plane of the sample, such as backscattered electrons. Although SCANNING TRANSMISSION ELECTRON MICROSCOPY also scans the specimen point by point with the electron beam, the image is constructed by detecting the electrons, or their interaction products that are transmitted through the sample plane, so that is a form of TRANSMISSION ELECTRON MICROSCOPY.Altitude: A vertical distance measured from a known level on the surface of a planet or other celestial body.Biodiversity: The variety of all native living organisms and their various forms and interrelationships.Ecosystem: A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)Species Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.