Tracheophytes [Gr. trakhoia: tube + phyton: plant]: Those plants with xylem and phloem, including psilophytes, club mosses,
horsetails, ferns, gymnosperms, and angiosperms.
Nontracheophytes: Those plants lacking well-developed vascular tissue; the liverworts, hornworts, and mosses.
Gymnosperm (jim´ no sperm) [Gr. gymnos: naked + sperma: seed]: A plant, such as a pine or other conifer, whose seeds do
not develop within an ovary (hence, the seeds are "naked").
Angiosperm (an´ jee oh spurm) [Gr. angion: vessel + sperma: seed]: One of the flowering plants; literally, one whose seed is
carried in a "vessel" (i.e., fruit).
Middle lamella: A layer of polysaccharides that separates plant cells; a shared middle lamella lies outside the primary walls of
the two cells.
Primary wall: Cellulose-rich cell wall layers laid down by a growing plant cell.
Secondary wall: Wall layers laid down by a plant cell that has ceased growing; often impregnated with lignin or suberin.
Lignin: The principal noncarbohydrate component of wood, a polymer that binds together cellulose fibrils in some plant cell
Suberin: A waxlike lipid that acts as a barrier to water and solute movement across the Casparian strip of the endodermis.
Suberin is the waterproofing element in the cell walls of cork.
Plasmodesma (plural: plasmodesmata) [Gr. plassein: to mold + desmos: band]: A cytoplasmic strand connecting two adjacent
Pits: Recessed cavities in the cell walls of a plant vascular element where only the primary wall is present. facilitating the
movement of sap between cells.
Parenchyma (pair eng´ kyma): A plant tissue composed of relatively unspecialized cells without secondary walls.