plant structure and growth
DESCRIPTION
Plant Structure and Growth. Overview. Lifecycles Annual, biennial, perennial Basic Plant parts Plant cell walls, simple tissue types Plant growth: Meristems Primary Tissues Primary growth – apical meristems Secondary growth – lateral meristem Secondary tissues. - PowerPoint PPT PresentationTRANSCRIPT
Plant Structure and Growth
Overview
Lifecycles– Annual, biennial, perennial
Basic Plant parts
Plant cell walls, simple tissue types
Plant growth:– Meristems– Primary Tissues– Primary growth – apical meristems– Secondary growth – lateral meristem – Secondary tissues
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.
bolting
Basic Plant Parts
• Shoot system: photosynthesis, reproduction– 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 nutrients.– Roots, root hairs– Mycorrhizae– Nitrogen fixing bacteria
Angiosperm Diversity
Amborella trichopoda Water lily (Nymphaea “Rene Gerard”)
Star anise (Illicium floridanum)
BASAL ANGIOSPERMS
HYPOTHETICAL TREE OF FLOWERING PLANTS
MAGNOLIIDS
Am
bore
lla
Wat
er li
lies
Star
ani
sean
d re
lati
ves
Mag
nolii
ds
Mon
ocot
s
Eud
icot
s
Southern magnolia (Magnoliagrandiflora)
Orchid(Lemboglossumrossii)
MonocotCharacteristics
Embryos
Leafvenation
Stems
Root
Pollen
Flowers
Pollen grain withone opening
Root systemUsually fibrous(no main root)
Vascular tissuescattered
Veins usuallyparallel
One cotyledon Two cotyledons
Veins usuallynetlike
Vascular tissueusually arranged
in ring
Taproot (main root)usually present
Pollen grain withthree openings
Zucchini (CucurbitaPepo), female(left) and male flowers
Pea (Lathyrus nervosus,Lord Anson’s blue pea),a legume
Dog rose (Rosa canina), a wild rose
Pygmy date palm (Phoenix roebelenii)
Lily (Lilium“Enchant-ment”)
Barley (Hordeum vulgare), a grass
AntherStigma
Californiapoppy(Eschscholziacalifornica)
Pyrenean oak(Quercuspyrenaica)
Floral organsusually in
multiples of three
Floral organs usuallyin multiples of
four or fiveFilament Ovary
EudicotCharacteristics
MONOCOTS EUDICOTS
Fig. 35.2
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.
Fig 35.11
Xylem
• Sclerenchyma• Dead at maturity• Hollow• Grows to size
first then makes secondary cell wall
• Tracheids• Vessel elements• Secondary xylem
is true wood.• Conducts water
from roots to leaf
Young Xylem
• We’ll go over different types in lab
• Transports sugar solution from source to sink.• Parenchyma-Living tissue, uses active
transport.• Sieve tube members and companions cells
Phloem
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 function.
Fig 35.7
Plant cell wall structure• Adjoining cells held together by middle
lamella (polysaccharides of pectin)• Cells first make thin, flexible primary cell
walls.• 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 wall.
• Plasmodesmata connect cytoplasm between neighboring cells through cell walls.
Fig 6.28
Cell Elongation
• 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 shape
Plane of symmetry
Plant Growth• 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 lateral meristems.– 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
Fig. 35.12
Fig. 35.17
Apical Meristem
• Divides cells that form primary meristem tissues– Protoderm – further divides to
make dermal layers– Procambium – divides to form
xylem and phloem, residual layer becomes vascular cambium
– Ground Meristem – forms pith and cortex
• Plants grow like building a brick wall- add bricks at top (primary growth), then add girth to sides (secondary growth).
Primary growth
• Herbaceous – no true wood• May have tough parts –
Collenchyma or Sclerenchyma.
• All cells derived from apical meristem
• 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 instructor.
• How far off the ground are your initials then?
Secondary Growth• In Ferns, Gymnosperms and Eudicots, not in
monocots• Vascular cambium layer begins to form.
– Divides off more cells.– Cells to the inside become secondary xylem
(wood) Cells to outside become secondary phloem.
• Adds girth, pushing outer layer farther out.• Parenchyma in phloem rays fill-in space
until cork cambium starts making bark.
Fig. 35.20
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 wood).
• Under water stress late in the season xylem cells very narrow (late wood).
• Evidence of past climates, period of drought.
Monocot and Eu-dicot
• Monocots do not have secondary growth.– 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.