Arabis: A plant genus of the family BRASSICACEAE. Member species are ornamentals grown for their numerous small white, yellow, pink, or purplish flowers.Nepovirus: A genus of polyhedral plant viruses of the family COMOVIRIDAE causing ringspots and spotting on leaves or sometimes symptomless infection. Transmission occurs by seeds, soil nematodes, or experimentally by mechanical inoculation. Tobacco ringspot virus is the type species.RNA, Satellite: Small, linear single-stranded RNA molecules functionally acting as molecular parasites of certain RNA plant viruses. Satellite RNAs exhibit four characteristic traits: (1) they require helper viruses to replicate; (2) they are unnecessary for the replication of helper viruses; (3) they are encapsidated in the coat protein of the helper virus; (4) they have no extensive sequence homology to the helper virus. Thus they differ from SATELLITE VIRUSES which encode their own coat protein, and from the genomic RNA; (=RNA, VIRAL); of satellite viruses. (From Maramorosch, Viroids and Satellites, 1991, p143)DNA, Chloroplast: Deoxyribonucleic acid that makes up the genetic material of CHLOROPLASTS.Mosaic Viruses: Viruses which produce a mottled appearance of the leaves of plants.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)OregonConiferophyta: A plant division of GYMNOSPERMS consisting of cone-bearing trees and shrubs.Trees: Woody, usually tall, perennial higher plants (Angiosperms, Gymnosperms, and some Pterophyta) having usually a main stem and numerous branches.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Soil: The unconsolidated mineral or organic matter on the surface of the earth that serves as a natural medium for the growth of land plants.World War I: Global conflict primarily fought on European continent, that occurred between 1914 and 1918.Rhododendron: A plant genus of the family ERICACEAE.Acacia: A plant genus of the family FABACEAE. The gums and tanning agents obtained from Acacia are called GUM ARABIC. The common name of catechu is more often used for Areca catechu (ARECA).Naval Medicine: The practice of medicine concerned with conditions affecting the health of individuals associated with the marine environment.Ships: Large vessels propelled by power or sail used for transportation on rivers, seas, oceans, or other navigable waters. Boats are smaller vessels propelled by oars, paddles, sail, or power; they may or may not have a deck.