Cells and Tissues of the Plant Body Chapter 23
Origin of Primary Tissues • Primarygrowth- formation of primary tissues. • Primary plant body.
Growth and Development • Development- the sum total of events that lead to the formation of the plant body. • Growth- an irreversible increase in size. • Cell division • Cell enlargement • ApicalMeristems- regions of tissue at the tips of shoots and roots that forms new cells. • Meristematic tissue. • Much of the plant undergoes unlimited or prolonged growth of the apical meristems= indeterminate.
Morphogenesis and Differentiation • Morphogenesis- the development of form. • Differentiation- a process by which a relatively unspecialized cell undergoes a progressive change to form a more specialized cell.
Internal Organization of the Plant Body • Tissue- a group of similar cells organized into a structural and functional unit. • TissueSystem- a tissue or group of tissues organized into a structural and functional unit; larger units of the plant body. • There are 3 Tissue Systems • Ground • Vascular • Dermal
Ground Tissue • Parenchyma • Polyhedral to round in shape. • Occur throughout the plant body. • Photosynthesis, storage, and secretion. • Collenchyma • Elongate in shape. • Occur beneath the epidermis in young stems. • Support young growing tissues. • Sclerenchyma- fibers and sclereids. • Long or stellate in shape. • Occur throughout the plant body. • Support (strengthen) and storage.
Vascular Tissue #1 • Xylem- principal water-conducting tissue in vascular plants; dead at maturity; lignified. • Tracheary Elements • Tracheid- elongate and tapering; pits, but no perforations; seedless vascular plants, gymnosperms, and some angiosperms. • Vesselelement- elongate; pits and perforations; angiosperms.
Vascular Tissue #2 • Phloem- principal food-conducting tissue in vascular plants; living at maturity; not lignified. • Gymnosperm Sieve Elements • Sieve cell- elongate & tapering; with sieve areas. • Albuminous cell- elongate & tapering; delivers substances to sieve cells. • AngiospermSieve Elements • Sieve-tube element- elongate & tapering; with a sieve plate. • Companion cell- variable; delivers substances to sieve-tube elements.
Dermal Tissue • Epidermis- outermost cell layer of the primary plant body. • Variable in shape; guard cells and trichomes. • Outermost layer of plant body. • Protective (cuticle and water loss) and aeration (stomata). • Periderm- secondary protective tissues. • Rectangular in shape; cork cells. • Beneath the epidermis. • Protective and aeration (lenticels); replaces epidermis.