Vegetative Parts

The main vegetative organs of plants that we will be talking about are

• Roots

• Stems

• Leaves

• Vegetative parts of plants that we eat for nourishment are known as vegetables

Plant Tissues

Ground Tissue Types

Meristem Tissue

Plants Need

1. Oxygen

2. Carbon Dioxide

3. Sunlight

4. Water

5. Nutrients (essential elements)

Why? You ask……..

• Photosynthesis

• Respiration

• Growth

• Development

• Reproduction

Plant parts.

Crown (leaf area)

Trunk (stem)

Roots

Crown (leaf area)Branches

Twigs

Leaves

Flowers

Fruit (seeds)

Crown (leaf area)Captures sunlight and carbon dioxide (for photosynthesis) , regulates water loss (transpiration), has reproduction organs and produces seeds.

Transpiration moves water and essential elements through a plant.

CO2 + H2O ----- CH2O + H2O + O2

Photosynthesis is a primary function in plants

Note: sugar.

Respiration is the burning of nutrients for energy by the cells

Note: sugar.

All parts of plant carry on respiration

Let’s look at the 3 main plant organs in more detail

• Leaves

• Stems

• Roots

Leaf

Cuticle

• Waxy layer

• Controls water loss by “waterproofing” the leaf

• Upper and lower

Epidermis

• Protects the leaf surface

• It is the “skin” of the leaf

• Holds in moisture also

• Upper and lower

Control gas entry/exit in leaves

Mostly in lower epidermis !

Stomata, Pea Leaf Stoma, Vicea sp. (SEM x3,520).

Mesophyll

• Cells with chloroplasts filled with chlorophyll that carry out photosynthesis– Palisade cells are long, upright, erect, and

packed like sardines. Most photosynthesis takes place here.

– Spongy cells are rounded and irregular and loosely packed with a lot of air spaces for movement of gases. Less photosynthesis here because there are fewer chloroplasts.

Veins

• Bundles of vascular tissue– Xylem carrying water and nutrients to leaf

cells– Phloem carrying food to storage sinks– Sheathing cells to enclose and protect the

vascular tissue

Trunk(stem)Heartwood

Xylem

Cambium

Phloem

Bark

Trunk, (stem)Transports water, food and other essential elements, stores energy, elevates and displays leaves to sun

(monocot)

Woody

(Dicot)

Herbaceous

In woody stems, the vascular cambium produces phloem on the outside (next to the bark) and xylem on the inside. Old xylem is the “wood” and exhibits the annual rings of growth

Roots

RootsCollect water and essential elements, anchor plants, store food.

RootsRoot branches (tap root, clustered and fibrous roots)

Root hairs

Taproot – one main vertical root and branches from it

Fibrous roots – many branches of about the same size/length; like the

grasses

Fascicled/clustered roots – similar to fibrous but of many varying sizes

Vascular tissue arrangement varies

Dicot root

Monocot root.

Roots1. 95% of roots in top foot of soil.

2. Biggest limiting factor to root growth is oxygen.

3. Roots often extend three times the distance of the branches.

Water is absorbed by diffusion into the root hairs then to the xylem of the root. It is then moved by cohesion of water molecules and capillary action up the stem xylem

Ideal SoilA) mineral material 45%

B) air 25%

C) water 25%

D) organic material 5%

note:

air + water = pore space

or

25% + 25% = 50% pore space

Remember roots carry on respiration so they need oxygen, too.

StressStress occurs often occurs when a plant won't get enough of what it needs. . .

Sunlight, water, essential elements, oxygen to roots etc.

Transport in Plants