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Plant StructureAnd Growth
The Plant Body is Composed of Cells and
Tissues•Tissue systems (Like Organs)
–made up of tissues•Made up of cells
Plant Tissue Systems• ____________________
photosynthesisstoragesupport
• ____________________conductionsupport
• ___________________Covering
Ground Tissue System
Vascular Tissue System
Dermal Tissue System
Ground Tissue System
• ___________ Tissue• Collenchyma Tissue• Sclerenchyma Tissue
Parenchyma
Parenchyma Tissue
• Made up of Parenchyma Cells
• __________ Cells• Primary Walls• Functions
– photosynthesis– storage
Living
Collenchyma Tissue
• Made up of Collenchyma Cells
• Living Cells• Primary Walls are
thickened• Function
– _Support_____
Sclerenchyma Tissue
• Made up of Sclerenchyma Cells
• Usually Dead• Primary Walls and
secondary walls that are thickened (lignin)
• _________ or _________
• Function– Support
FibersSclerids
Vascular Tissue System
• Xylem – H2O
– ___________
– Vessel Elements
• Phloem - Food– Sieve-tube
Members– __________
Tracheids
Companion Cells
Xylem • Tracheids– dead at maturity– pits - water
moves through pits from cell to cell
• Vessel Elements– dead at maturity– perforations -
water moves directly from cell to cell
Phloem• _____________
– alive at maturity– lack nucleus– Sieve plates - on
end to transport food
• _____________– alive at maturity– helps control
sieve-tube member cell
Sieve-tube member
Companion Cell (on the side)
Sieve-tube members
Companion Cells
Dermal Tissue System• Epidermis
– Single layer, tightly packed cells– Complex Tissue – Does different things
in different areas (roots vs. leaves)– usually transparent– secretes cuticle
• ___________ – – replaces epidermis in woody plants– protectionPeriderm
Plant Systems
• ____________– Tap Root– Lateral Roots
• ____________– Stems
• Nodes (leaves are attached)
• Internodes
– Leaves• blades• petioles
– Buds• Terminal (apical)• Axillary
Root System
Shoot System
Plant Growth
• ______________ Tissue– generates cells for new
growth (like stem cells in animals)•apical meristems•lateral meristems
Meristematic
Apical Meristems• increases length called primary
growth–___________ - gives rise to dermal tissue
–________________- gives rise to ground tissue
–_____________ - gives rise to vascular tissue
Protoderm
Ground Meristem
Procambium
Lateral Meristems• increases girth called secondary
growth–__________________- produces secondary xylem and secondary phloem
–______________- produces cork (outer most layer of bark)
Vascular Cambium
Cork Cambium
Pine Tree w/ 8 Cotyledons!
The Root System• Functions
– anchor plant– absorb minerals, water and nutrients– store food
• Systems– ____________ - one large root with
smaller lateral roots (dicots)– ____________- threadlike roots
(monocots)
Tap roots
Fibrous roots
Root Structure• Four Regions
– _________– protection, also secrete polysaccharide slime to lubricate
– Region of ___________- new cells– Region of __________ - cells get
longer– Region of _________ - cells begin to
specialize
Root Cap
Cell Division
Elongation
Maturation
Root Tissue• Protoderm - gives rise to the
epidermis• Ground Meristem
– Cortex (external to vascular tissue)
• Procambium - gives rise to the _______ (the vascular tissue of a root or stem)– xylem and phloem
– may include pith (parenchyma cells surrounded by vascular tissue)
Stele
Dicot Root vs. Monocot
“Pith” – central core of parenchyma cells surrounded by xylem and phloem
Xylem (larger, in red)
Phloem (smaller, greenish)
Endodermis
Pericycle – one layer IN from endoderm, gives rise to lateral roots
Modified Roots
• Food Storage– carrots, sweet
potatoes, yams
• Water Storage– pumpkin family
• Propagative Roots– cherries, pears
• Pnematophores– mangroves
• Aerial Roots– orchids
• Buttress Roots– tropical trees
• Haustoria– dodder
Shoot System
The Shoot System• Made up of Stems, Leaves,
Flowers, Fruits– Stems - support, conduction, growth– Leaves - photosynthesis– Flowers - pollination– Fruits - seed protection, dispersal
Stems (Primary Growth)• Protoderm - gives rise to the
epidermis• Procambium - gives rise to the
stele– xylem and phloem in vascular
bundles•dicots - found in ring•monocots - scattered
throughout– includes “pith” in dicots
• Ground Meristem– Cortex
____________– stele (vascular tissue) divided into strands in stems and
leaves
Xylem
Phloem
Sclerenchyma cells
Vascular Bundle
Dicot Stem Vs. Monocot (35.16)
How can you tell root from stem?
Vascular Bundle
Ground Tissue
(Pith)
(Cortex)
Stems (Secondary Growth)• Occurs to increase girth (thickness)
– Vascular Cambium• produces secondary xylem and
secondary phloem
– Cork Cambium• produces cork and phelloderm (thin
layer of parenchyma cells)• together these structures are called
periderm (Cork Cambium, cork, phelloderm)
Secondary Growth
Vascular cambium
Derivative
Secondary Growth of
a Stem
Secondary Growth of a Stem (Inside to Outside)
• Pith• Primary
Xylem• Secondary
Xylem (wood)
• Vascular Cambium
• Secondary Phloem
• Primary Phloem
• Cortex• Phelloderm• Cork Cambium• Cork (outer
layer of bark)
Peri
derm
Older, inner layers of 2° Xylem – no longer transport water
Younger, outer layers of 2° Xylem still function in transport
All tissue outside vascular cambium
Missing cortex and phelloderm!
___________ (Early) growth occurs more
quickly. Cells are large and thinwalled and have less strength.
Summerwood (Late) growth occurs more slowly. Cells are thicker, more dense, and stronger.
Springwood
Secondary Growth of
a Stem
Modified Stems• __________ - horizontal
stems above the ground (strawberries)
• Rhizomes - horizontal stems below the ground (Irises)
• Tubers - swollen areas of rhizomes or stolons (Potatoes)
• Bulbs & Corms - vertical shoots under ground (onions, garlic w/ mod storage leaves)
• _____________ - cactus pads
Stolons
Cladophylls
Leaf Structure
Leaves• Epidermis
– __________ - openings on underside of leaf
– Guard Cells - surround stomata– Cuticle - waxy coating excreted
by epidermis
• Mesophyll - middle of leaf – ___________ - photosynthesis– Spongy layer - gas exchange
Stomata
Palisade Layer
Modified Leaves• ___________-
attachment• Bracts –modified
leaves that surround a group of flowers
• Spines - protection
• Storage Leaves - succulents
Tendrils