roots and stems

a vascukar plant consist of

root systems (which are underground)

In roots systems , roots

anchor the plant and absrob water and minerals

zones of roots (bottom to top)

(bottom to top)

root cap

zone of cell division

zone of elongation

sone of maturation

root cap contains

two types of cells that are formed continously by the root apical meristem

Is there an equivalent structure to the root cap in stems?

No, stems do not have an equivalent structure to the root cap.

What forms the cells of the root cap?

The root apical meristem continuously forms the cells of the root cap.

What are the two types of cells found in the root cap?

Columella cells and root cap cells.

columella cell

nner cells that perceive
gravity (gravitrophism) and also respond to
pressure in the soil

root cap cells

outer and lateral layer;
protects the root apical meristem; lubricates
the root by producing mucigel

Mucigel

polysaccharide that lubricates to push its
way through the soil

zone of cell division derived from

rapid dividsion of the root apical meristem

What happens in the Zone of Cell Division?

Cells rapidly divide and newly formed cells increase in length, lengthening the root.

What do apical meristem daughter cells subdivide into?

They are subdivided into the three primary tissues. leaves, flowers, shoots

What is the main function of the Zone of Cell Division?

To produce new cells for root growth and development.

In the zone of elongation, cells
become

several times longer
than wide and increase slightly
in width

In the zone of maturation, elongated cells become

differentiated into specific cell types

what are the specific cell types

epidermal

root hair

parenchyma

endodermal

pericycle

xylem

phloem

In the Zone of Maturation, what do root surface cells become?

They become epidermal cells.

What structures are included among the epidermal cells in the Zone of Maturation?

Root hairs and nonhair cells.

eudicot roots have

xylem

monocot roots have

pith (ground tissue)

function of pith

support
and structure; stores sugars
in parenchyma cells.

What do root surface cells become in the zone of maturation?

They become epidermal cells, forming the outer layer of the root.

What are the two types of epidermal cells formed on the root surface?

Root hair cells and nonhair cells.

What is the function of root hair cells?

To absorb water and minerals from the soil and increase the root’s surface area.

What is the function of nonhair epidermal cells?

To protect the root and provide structure.

What do cortex cells become and what is their role?

: Parenchyma cells that store food (starch) and allow movement of water and minerals inward.

What do endodermal cells do?

They regulate the movement of water and minerals into the vascular tissue.

What do pericycle cells do?

They can divide and form lateral roots (side roots).

What are the vascular tissues that form in the zone of maturation?

Xylem and Phloem.

What is the function of xylem and phloem?

Xylem: Carries water and minerals upward.

Phloem: Carries sugars and nutrients throughout the plant.

monocot or eudicot

eudicot

monocot or eudicot

monocot

secondary growth in roots 

lateral meristems

In roots, what gives rise to lateral meristems and roots

pericycle

Secondary growth is the process in which

vascular cambium and cork cambium produce new tissues that make the plant thicker (increase in girth, not length).

Secondary xylem =

wood

Secondary phloem =

inner bark

Cork cambium

• forms outer bark (mostly dead protective tissue)

casparian strip

contains a fatty, waterproof compound called suberin(cork) that

blocks the passage of water and minerals beteween endodermal cells

What is the Casparian strip made of?

A fatty, waterproof compound called suberin.

Where is the Casparian strip located?

In the walls of endodermal cells in plant roots.

What is the function of the Casparian strip?

To block the movement of water and minerals between endodermal cells, forcing them to pass through the cells instead.

Why is the Casparian strip important?

It ensures the plant can control which substances enter the xylem (the vascular tissue).

What happens because of the Casparian strip?

Water and minerals must pass through cell membranes (the symplastic pathway) rather than between cell walls (the apoplastic pathway).

What element is suberin primarily made of?

Carbon — making it hydrophobic (water-repelling).

The Casparian strip acts like

a filter or gatekeeper — it controls what and how much water and minerals enter the xylem.

two main types of roots

fibrous roots

taproot

fibrous root

many similarly sized roots

taproot

single large root with small branch roots

Fibrous root: grass

taproot: carrot, beet

modified stems(not roots): potato (tubur), onion(bulb)

holes on potatoes

axillary buds

prop roots

Keep the plant upright (corn)

aerial roots

An anchor plant obtains water from the air (orchids)

pneumatophores

used for plants growing in high salt muds of wet soil

facilitate oxygen uptake in O2-poor soil (mangrove tree)

buttresses

help anchor large plants, provide stability

common in the tropics

mesquite lateral root

what kind of root 

bayan tree (prop root)

what kind of root

buttress root

water storage roots

store water

food storage roots

store carbohydrates

haustoria

penetrates host plant tissue (mistletoe)

contractile roots (lily bulbs)

Pull the plant deeper into the soil

due to erosion

shoot system

supports stems, leaves, and flowers

aboveground

What does the shoot apical meristem (SAM) initiate?

: It initiates stem tissue.

What does the shoot apical meristem produce?

It produces primordia (early structures that will develop into new organs).

What do primordia develop into?

They develop into leaves, other shoots, and even flowers.

Where is the shoot apical meristem located?

At the tip of the shoot (the growing point of stems).

What is the main function of the shoot apical meristem?

To produce new cells for shoot growth and form new organs like leaves and flowers.

nodes

area where new leaf will grow

alternate node

1 leaf per node

opposite periwinkle node

2 leaves per node

whorled sweet woodruff node

3 leaves or more per node

bud scales

protect terminal buds

terminal bud 

apical bud

makes the branch or twig longer

axillary bud

lateral bud

gives rise to branch

axil

angle between leaf petiole and stem

terminal bud scale scars 

where bud scales were attached

bundle scar

where xylem and phloem enter the leaf

leaf scare

where leaf was attached

lenticels

gas exchanges in woody stems

A leaf consists of both a blade and a petiole.

true

If a leaf does not have a petiole, it has no axil.

false

• The axil is the angle between the stem and the leaf (where axillary buds form).

• Even if a leaf is sessile (no petiole), it still has an axil.

A branch with 5 nodes has how many internodes?

4 internodes

internodes:stem segments between two nodes.

herbaceous eudicot stems

stems that die back each year

in herbaceous eudicot stems, vascular bundles are

arranged in a circle in cross sections of the eudicot stem

in herbaceous eudicot stems,vascular cambium forms 

between primary xylem and phloem

in monocot stems, vascular bundles are

scattered

monocot stems have no

vascular cambium (no secondary growth)

Ring barking or girdling

keeps the cambium from growing back

Girdling means

removing or destroying the cambium layer

Why Girdling kills a tree 

Stops the downward transport of sugars

Roots fail → whole tree weakens:

Cambial regeneration is prevented

• Stops downward transport of sugars: Phloem carries sugars made in the leaves down to roots. If phloem continuity is lost, roots starve.

• Roots fail → whole tree weakens: Without sugars, roots can’t maintain themselves or absorb water well, which eventually causes the crown to decline.

• Xylem is not immediately severed by superficial girdling, so water may still move for a time — this is why death can take months to years depending on the tree and extent of damage.

• Cambial regeneration is prevented if the ring is continuous and complete; partial damage can sometimes be healed if cambium bridges form or callus tissue grows back.

ring barking/girdling is a common way

to kill invasive species

gives animals time to evolve

In woody eudicots, the cork cambium arises

in the outer

   cortex

In woody eudicots, where does the cork cambium arise?

It arises in the outer cortex.

in woody eudicots, What does the cork cambium produce on the outside?

Cork cells.

in woody eudicots, What does the cork cambium produce on the inside?

Phelloderm cells (parenchyma-like cells).

in woody eudicots, What three layers make up the periderm (outer bark)?

Phelloderm, cork cambium, and cork cells.

What is another name for the periderm?

The outer bark.

Root or Stem? What type?

stem eudicot