Vegetative Parts The main vegetative organs of plants

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.

Photosynthesis is a primary function in plants CO 2 + H 2 O ----- CH 2 O + O 2 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 x 3, 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

Roots Collect water and essential elements, anchor plants, store food.

Roots Root 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.

Roots 1. 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 Soil A) 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.

Stress 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