35 Plant Anatomy
Transcript 35 Plant Anatomy
Plant Structure and Growth
– Annual, biennial, perennial
Basic Plant parts
Plant cell walls, simple tissue types
Primary growth – apical meristems
Secondary growth – lateral meristem
Flowering Plant Lifecycles
• Annual – germinates, flowers set seeds and
dies in one growing season
• Biennial- germinates grows first season,
storing up energy underground. Second
spring plant use energy to quickly bloom
(bolting) set seed and die.
• Perennial grows for several seasons until
mature, Blooms and sets seed for years.
Basic Plant Parts
• Shoot system: photosynthesis,
– Stems with nodes
– Leaves - axilliary bud at base of each
– Flowers and fruits (cones in gymnosperms)
• Root system ; Anchors plant; Storage
organs; absorption of water and
– Roots, root hairs
– Nitrogen fixing bacteria
Star anise (Illicium
Water lily (Nymphaea
Southern magnolia (Magnolia
HYPOTHETICAL TREE OF FLOWERING PLANTS
Pygmy date palm
Barley (Hordeum vulgare),
(no main root)
Dog rose (Rosa canina), a wild rose
Taproot (main root)
Pollen grain with
Pea (Lathyrus nervosus,
Lord Anson’s blue pea),
Pollen grain with
multiples of three
Floral organs usually
in multiples of
four or five
(left) and male flowers
Simple Plant Tissue Types
• Tissues- cells with a common structure and
function and specialized connections.
• Parenchyma- Soft, rounded cells with thin
primary cell walls, air spaces between cells
– Many are Totipotent Cells- undifferentiated that
can still divide
– Some are specialized: chlorenchyma, phloem
• Collenchyma- irregularly thicken primary cell
wall, no air spaces. Elastic support.
• Sclerenchyma – rigid secondary cell wall.
May have no cytoplasm left: Wood, Xylem,
vessels, fibers, tracheids. Also seed coat.
Dead at maturity
Grows to size
first then makes
is true wood.
from roots to leaf
• We’ll go over
different types in
• Transports sugar solution from source to sink.
• Parenchyma-Living tissue, uses active
• Sieve tube members and companions cells
Plant Tissues comprise Organs
• Dermal tissues cover the plant
– Epidermis, stomata, trichomes, bark
• Vascular Tissues transport materials
– Xylem carries water
– Phloem carries sugar solution
• Ground Tissues – metabolic functions, growth
– Meristems, photosynthesis, storage
• Organs-groups of tissues forming a larger
structure, with a common structure and
Plant cell wall structure
• Adjoining cells held together by middle
lamella (polysaccharides of pectin)
• Cells first make thin, flexible primary cell
• Plant cells can still enlarge / divide with
primary cell wall.
• Some cells lay down three rigid secondary
cell wall layers with ligin inside primary cell
• Plasmodesmata connect cytoplasm between
neighboring cells through cell walls.
• How cellulose microfibrils are laid down
determine the direct of elongation.
• Elongation takes place when a cell only
has primary cell wall.
• Once proper size and shape is attained,
secondary cell wall material is added
inside the primary cell wall.
Plane of Cell division
• Determines the cell
Plane of symmetry
• Indeterminate growth
• Primary growth: cells derived from the apical
meristems (both root and shoot).
– Makes the plant grow taller and roots deeper.
– Makes leaves, flowers fruits
• Secondary Growth: cells derived from the
– Adds girth to plant
– Vascular cambium makes secondary xylem
(wood) and secondary phloem.
– Cork cambium adds to bark
• Meristems- localized areas of cell divisions
– Plants grow in zones, not all over whole organism
• Divides cells that form primary
– Protoderm – further divides to
make dermal layers
– Procambium – divides to form
xylem and phloem, residual layer
becomes vascular cambium
– Ground Meristem – forms pith
• Plants grow like building a
brick wall- add bricks at top
(primary growth), then add
girth to sides (secondary
• Herbaceous – no true wood
• May have tough parts –
• All cells derived from apical
• Forms separate vascular
bundles in stem.
• You fall madly in love with you’re a lab mate
in 131 – and hand in hand you both carve you
initials 4 feet off the ground on the Bishop
Pine (Pinus muricata) in the turn-around by
the LS building.
• The Bishop Pine grows 3 feet a year.
• Two years later you return to DVC after
finishing up at UC Santa Cruz in Organismal
Biology to visit you old favorite Biology
• How far off the ground are your initials then?
• In Ferns, Gymnosperms and Eudicots, not in
• Vascular cambium layer begins to form.
– Divides off more cells.
– Cells to the inside become secondary xylem
(wood) Cells to outside become secondary
• Adds girth, pushing outer layer farther out.
• Parenchyma in phloem rays fill-in space
until cork cambium starts making bark.
Annular growth rings
• In temperate or wet /dry seasonal zones
• In spring new growth use a lot of water,
xylem cells grow very large (early
• Under water stress late in the season
xylem cells very narrow (late wood).
• Evidence of past climates, period of
Monocot and Eu-dicot
• Monocots do not have secondary
– Palm trees, bamboo - not true wood!!
• We’ll compare anatomical variation
between these groups in lab
– Learn differences between monocot , dicot
anatomy of leaves, stems, roots.