<descriptor thcode="2"><thesaurus thcode="2" name="USGS Thesaurus" scope="Topics and methods of scientific study carried out by USGS, with product types, scientific disciplines, geologic time, and types of institutional structure and activities.  Broad and shallow, used to help people find scientific information." creator="U.S. Geological Survey" rights="Public domain" edition="2.0" date="2020-01-09" codetype="number" prefix="topic" uri="https://www2.usgs.gov/science/USGSThesaurus" tblname="term" nonpref="nonpref" relterm="relterm" root_code="1" contact="pschweitzer"><category><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/><term thcode="25" code="29" name="distinct labels" parent="26" scope="Preferred labels (descriptor texts) are distinct within the thesaurus. A concept can be specified either by its unique identifier (code) or by the text of its descriptor."/><term thcode="25" code="16" name="hierarchical" parent="11" scope="Substantive broader-narrower relationships exist among the terms."/><term thcode="25" code="13" name="transitive" parent="12" scope="Narrower terms have an &quot;is a&quot; relationship with their broader terms, and generally can be described as part-of, type-of, or instance-of the broader term."/><term thcode="25" code="21" name="disciplines" parent="2" scope="Broad categories of human inquiry or activity, such as scientific disciplines."/><term thcode="25" code="20" name="methods" parent="2" scope="Actions taken to obtain or analyze information"/><term thcode="25" code="19" name="organizational functions" parent="2" scope="Things that organizations do, typically including various types of programs, projects, and services."/><term thcode="25" code="7" name="temporal" parent="2" scope="Terms indicate periods of time, such as chronostratigraphic units, named historical periods or intervals surrounding known historical events, or seasons."/><term thcode="25" code="5" name="theme" parent="2" scope="Terms indicate domains of human concern, such as scientific discipline, societal problems, or characteristics of earth, space, oceans, and living things."/></category><altlabel><altlabel>USGSThesaurus</altlabel><altlabel>USGSThesaurus</altlabel></altlabel></thesaurus><term thcode="2" code="127" name="botany" parent="650" scope="The science of plants."/><bt><term thcode="2" code="650" name="life sciences" parent="1019" scope="Branches of science that study living and fossil organisms."/><term thcode="2" code="1019" name="sciences" parent="1" scope="Major educational fields, fields of study, and professional groupings within USGS."/><term thcode="2" code="1" name="Categories" scope="Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."/></bt><nt><term thcode="2" code="865" name="palynology" parent="127" scope="Branch of botany concerned with the study of pollen and spores, especially fossil remains. These are used to study plant life and dispersal in geologic history and to date deposits."/><term thcode="2" code="890" name="phycology" parent="127" scope="Branch of biology concerned with the study of algae."/></nt><rt><term thcode="2" code="281" name="drilling and coring" parent="379" scope="Cutting into the subsurface, for example into underground strata, ice, or a tree trunk, to remove material for examination. Intended for broad use wherever coring is done. The combination of this term with other terms will convey the context of the activity."/><term thcode="2" code="372" name="ferns and fern allies" parent="1265" scope="Spore-bearing, vascular plants having leaves known as fronds."/><term thcode="2" code="401" name="flowering plants" parent="1265" scope="Plants known as angiosperms which periodically produce flowers which have various parts including sepals, petals, stamens, and carpels."/><term thcode="2" code="411" name="forest resources" parent="777" scope="Trees and associated vegetation available for human use.  Use for timber and other forest resources with economic value."/><term thcode="2" code="521" name="gymnosperms" parent="1265" scope="Seed-bearing woody vascular plants, such as the conifers (pine, spruce, fir, etc.), whose seeds are not enclosed in an ovary or fruit, but are exposed."/><term thcode="2" code="669" name="liverworts and hornworts" parent="801" scope="Simple green land plants of the phyla Bryophyta with leaves and a stem and always without roots."/><term thcode="2" code="760" name="mosses" parent="801" scope="Simple green land plants, member of the phyla Bryophyta, along with liverworts and hornworts.  They have leaves and a stem, but always lack roots."/><term thcode="2" code="767" name="mycology" parent="650" scope="Branch of biology concerned with the study of fungi."/><term thcode="2" code="801" name="nonvascular plants" parent="909" scope="Simple plants which lack conducting tissues known as vascular bundles, a group of specialized cells made up of xylem and phloem."/><term thcode="2" code="858" name="paleobotany" parent="861" scope="Branch of paleontology concerned with the study of fossil plants and plant life in the geologic past."/><term thcode="2" code="909" name="plants (organisms)" parent="843" scope="Organisms which belong to the plant kingdom. Commonly multicellular, they produce food through photosynthesis."/><term thcode="2" code="935" name="producers (organisms)" parent="841" scope="Organisms, chiefly green plants, which use inorganic elements, compounds, and light to produce their food (photosynthesis). They are a source of food for animals."/><term thcode="2" code="1265" name="vascular plants" parent="909" scope="Plants which have a specialized conductive system. Includes xylem and phloem: club mosses, ferns, cycads, gymnosperms, and angiosperms."/><term thcode="2" code="1266" name="vegetation" parent="841" scope="Plant life or general plant cover in an area."/></rt></descriptor>