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Cells and Tissues of the Plant Body
Chapter 23
Origin of Primary Tissues
• Primary growth- 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
• Apical Meristems- 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.
• Tissue System- 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 waterconducting 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.
– Vessel element- 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.
• Angiosperm Sieve 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.