Plant Tissues & Organs Systems Biology Lesson # 5 Plant Tissues & Organs Systems

4 Types of Plant Tissue 1. Meristematic Tissue Made of unspecialized cells capable of dividing by mitosis (the plant “stem cells” – but not just in the stem!) Found in several locations in the plant Responsible for growing new parts of the plant

4 Types of Plant Tissue 2. Epidermal Tissue Forms a protective outer coating both on top and underside of the leaf, and is clear and very thin Tiny openings called stomata, that allows carbon dioxide, water vapour, and oxygen into or out of the leaf easily Most stomata are found on the underside to minimize water loss.

4 Types of Plant Tissue 3. Ground Tissue The cells which make up the majority of the plant, and there function depends on where it is located In the stem – provides strength and support In the roots – stores food and water In the leaves – where photosynthesis occurs, called mesophyll

4 Types of Plant Tissue 4. Vascular Tissue Transports water and nutrients up and down the plant. Xylem - movement of water and minerals from the roots up through the stem to the leaves for photosynthesis Phloem - transports sugar produced in photosynthesis from the leaves to other parts of the plants to use as energy

Xylem & Phloem

Plant Organs Just as a group of specialized cells becomes a tissue, an organ is an organized group of tissues that performs a special function. Recall that a flowering plant is made up of four types of plant tissues: epidermal, ground, vascular, and meristematic, and they group together to form organs that perform special functions for the plant. There are four main organs in most plants:

The Roots Function: Tissues involved: Anchor the plant in the soil and allows the plant to grow above the soil without toppling over. Collect water from soil and transport it to them stem. Store food made in other parts of the plant. Tissues involved: Epidermal tissue at the bottom of the root, called the root cap, which protects the roots Meristematic tissue which allows the root to grow Ground tissue that provide strength and support to the roots.

The Leaves Function: Tissues involved: Accomplish photosynthesis – a chemical reaction in which carbon dioxide and water are converted into sugar and oxygen Tissues involved: Vascular tissue (xylem) carries water needed for photosynthesis from the root up the stem to the leaf, and the sugar produced is carried by the vascular tissues (phloem) to the rest of the plant Epidermal tissue contains stomata which allows carbon dioxide to enter the leaf and oxygen and excess water to exit the leaf Ground tissue called mesophyll is where the chemical reaction of photosynthesis actually takes place

Leaf Diagram

The Stem Function: Tissues involved: Transports water and nutrients throughout the plant Supports the leaves and flowers Tissues involved: Epidermal tissue allows for the exchange of gases and water vapour, while using a waxy substance called a cuticle that reduces water loss and provides protection. Ground tissue provides support and strength to the stem Vascular tissue within the stem transports substances through it to other parts of the plant

The Flower Function: Tissues involved: The reproductive structure of the plant – produces seeds through sexual reproduction The male organs are called stamens, and consist of a filament with an anther at the tip, which produces pollen (male sex cells). The female organ is the pistil, which contain the overy, style, and stigma, with the eggs (female sex cells) being in the ovary. When the pollen and egg unite, a fertilized egg becomes a seed. Some seeds are surrounded by a flesh called the fruit, others are simply encased in a hard shell Tissues involved: Meristematic tissue creates new cells. As the flower structure develops, the meristematic tissue differentiates to form other specific parts of the flower.

Flower Diagram

Plant Organ Systems Organ systems are organs that function together to carry out specific duties of the plant or animal. Plant organ systems are much less complex than animal organ systems. There are two organ systems in plants: the shoot system and the root system. The shoot system is everything above the ground, and the roots are everything below. Both organ systems are involved in the survival of plants, for example:

Plant Systems (continued) Getting Water: A plant’s roots push water up the stem, but not the entire way. Once the water is in the xylem, is it moved against gravity up the stem to the leaves through a process called transpiration. Transpiration is the evaporation of water through the stomata in the leaves. As each water molecule evaporates, a pull is created which draws more water up the xylem, so the plant is continuously hydrated. Changing Environment: When daylight hours increase, specialized cells record the changes and deliver chemical messages to the tissues to stimulate the production of a flower. Another example is when there is a lack of water or excessive heat, where chemical messages are sent to decrease the production of leaves which is where the most water loss occurs.

Videos Crash Course – Vascular Plants Crash Course – Plant Reproduction (skip first 6:40 minutes)