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