A Closer Look at Kingdom Plantae

I. Introduction (pp. 502 & 604) Plants are placed into groups based on structural and functional similarities, but all plants share the following characteristics: A. Plants are eukaryotic, multicellular organisms with organs & organ systems B. All plant cells have cell walls composed of cellulose

C. Plants are autotrophic, which means they can use energy from the sun to make glucose in photosynthesis. Photosynthesis takes place in the chloroplasts of plant cells. The equation for photosynthesis is CO2+H2O  C6H12O6 D. Plants are non-motile; therefore, special adaptations are required for reproduction

II Plant Structure & Growth (pp ) A. Plant Transport Larger plants must have a way to transport water, food and minerals. This is carried out by two type of vessels. Together the vessels (cells working together) make up a tissue in plants known as vascular tissue. Plants are divided into two groups, based on whether or not they have vascular tissue.

1. Xylem transports water & minerals from the root to the rest of the plant. *Water always moves 1 direction-from the roots->stem->leaves *Water evaporates from the plant through opening on the underside of the leaves called stomata 2.Phloem transports “food” (glucose) from the leaves to the rest of the plant. *It carries sugars in all directions *Sugar can be carried from where it is made (Usually the leaves) to where it is stored (usually stems and roots.)

III Plant Classification ( ) Plants are divided into two basic groups based on whether they contain vascular tissue: A. Bryophytes Bryophytes, or mosses, are the only group of plants that lack vascular tissue. This limits both the size and location of this group of plants. Mosses are small and typically live in moist areas. In addition, a moist climate is required because mosses have swimming sperm. The sperm must swim to the egg cell in order for fertilization to take place.

Bryophyte-Moss

B. Tracheophytes Tracheophytes are vascular plant which allows them to grow taller and live in drier climates. The tracheophytes are further subdivided based on the presence or absence of pollen, seeds, and fruit: Pterophytes-No pollen, no seeds, no fruits Pterophytes are commonly called ferns. Although ferns contain vascular tissue, they are still found predominantly in moist climates because the sperm must swim to the egg cell.

C. Tracheophytes with Seeds All other tracheophytes produce seeds. Seeds provide a tremendous reproductive advantage. A seed consists of an embryo surrounded by a tough protective coat. Advantages of Seeds a. Protection b. Nourishment-Starch is stored in the seed for developing embryo c. Dispersal-Easily spread by wind, animals, water; reduces competition for nutrients d. Dormancy-Seeds remain dormant or inactive until conditions are favorable

2. Seed Germination The first visible evidence that a seed is germinating is the emergence of the embryo’s root followed by the growth of an embryonic shoot that develops into the plant’s stem.

Types of Seed Plants 2. Gymnosperms-Have pollen and seeds, no fruit. The word “gymnosperm” means “naked seed” because the seed is not protected by a fruit. A unique characteristic of gymnosperms is the presence of cones. The largest and most common phyla is confiers which includes pines, spruce, cedar. Confiers have characteristic leaves called needles, which are modified to prevent water loss and minimize ice build-up. In addition, gymnosperms (and angiosperms) have “flying sperm” or pollen. So they are no longer tied to water for reproduction. 3. Angiosperms-Have pollen, seeds, and fruit

IV. Angiosperms-Tracheophytes with Seeds & Fruit (pp ) Angiosperms are the most complex and adaptable of all plant groups. They are also the most successful due to two important modifications: A. Fruit- A fruit is a mature ovary that contains one or more seeds. It provides the embryo with greater protection and nutrients than found in gymnosperm seeds. The fruit also increases seed dispersal because fruits are eaten by animals, seeds pass through the digestive tract and are eliminated. Some fruits are not intended to be edible.

B. Flower ( ) The flower is the reproductive system of the angiosperm. It enhances pollination, which occurs as a first step to fertilization. 1. The male reproductive organ is the stamen, which consists of the anther and filament. Pollen, is produced by the anther and contains the sperm cells.

2. The female reproductive organ is the pistil, which consists of the sticky top called the stigma, the neck called the style, and the base called the ovary. The ovary contains the female gametes ovules or eggs. During pollination, pollen is transferred from the anther to the stigma. When a pollen grain lands on a stigma, it sends out a pollen tube that grows through the style to the ovary. Once the sperm reached the egg cell, fertilization take place.

3. The petals are usually colorful to attract pollinators. 4. The sepals are protective green modified leaves at the base of a flower. They protect the bud before the flower blooms.

C. Types of Angiosperms 1. Angiosperms are further classified into two groups based on characteristics. Monocots include plants such as grasses, corn, lilies. Monocot seeds have one cotyledon (seed leaf). These are seeds that cannot be split in half, like a piece of corn. Dicots are more abundant and include plants such as roses, oak trees, etc. Dicots have two cotyledons. These seeds can be split in half like peanuts and beans

Plant Structure ( ) C. Roots anchor the plant, absorb water and minerals from the soil, and transport these materials to the stem. Some plants also store food in their roots. Each root has root hairs, tiny extensions of epidermal cells that increase surface area for water absorption. *Water is absorbed into the plant by the process of osmosis

There are two kinds of roots Taproots- a large, main, primary root. Example = carrot Fibrous- branching, secondary roots. Example = grass

D. Stems Stems have 2 main functions Supporting leaves and flowers. Transporting water via xylem and food via phloem Some plant stems have the additional job of photosynthesis

E. Leaves * The actual leaf is the organ. It is attached to the stem by a thin structure called a petiole. *The vascular tissue enters the leaf through the petiole and forms the veins of the leaf. Leaves are the main organ for photosynthesis. They have a large surface area for maximum light absorption. The structures of a leaf include: A. Cuticle-Waxy covering to prevent water loss B. Epidermis-Outermost layer of cells; prevents injury, infection

A. Mesophyll-Photosynthetic layer of leaf 1. Palisade layer-Upper portion of mesophyll with closely packed cells; site of most photosynthesis 2. Spongy layer-Underside of leaf; loosely-packed cells to allow for exchange of CO2 and O2

D. Vein-xylem & phloem E. Stomata-Opening in underside of leaf that allow CO2 (carbon dioxide) to enter; O2 (oxygen) to exit

F. Guard Cells-Control size of stomata. Work to preserve balance between allowing for gas exchange without losing too much water. “Plant sweat” is known as transpiration.

B. Plant Growth 1. Primary Growth-Lifelong growth occurs at the tips of the stem and the end of the roots in tissue called the meristem *Apical meristem is located at the tips of stems and roots (groups of undifferentiated cells that divide to produce increased length of stems and roots)

2.Secondary Growth- Trees and some other plants have a second type of meristem tissue; allow them to grow in width or girth. *Cambium is the meristem tissue that allows plants to get wider.

2. Angiosperms may also be classified according to the length of their life cycle. Annual- flowering plant that completes a life cycle within one growing season. Biennial- flowering plant that completes its life cycle in two growing seasons. Perennial- flowering plant that live more than 2 years.

V. PLANT HORMONES AND RESPONSE A hormone is a chemical substance that is produced in one part of an organism and affects another part of the same individual. Plant hormones are chemical substances that control a plant’s patterns of growth and development, and the plants responses to environmental conditions. A. Hormones 1.Auxins-Produced in the apical meristem; transported throughout the rest of the plant. Works by “stretching” cells to elongate shoot, stem, and/or root. 2.Cytokinins-Produced in growing roots and in developing fruits/seeds. Cytokinins stimulate cell division,growth of lateral buds, and dormant seeds to sprout. Cytokinins often produce effects opposite to those of auxin.

3. Gibberellins- produce dramatic increases in size, by stimulating growth and increasing size. 4. Ethylene-auxin controlled hormone that stimulates the ripening of fruit. 5. Abscisic Acid-prevents growth. Used to maintain seed dormancy and tolerate drought.

A. Tropism- response of a plant to an environmental stimulus. 1. Phototropism - is the tendency of a plant to grow toward a source of light. Auxin production increases in the shaded part of the stem; causes the dark side of the stem to elongate  stem to bend toward the light.

2. Gravitropism - response to gravity due to action of auxin. This assures that roots grow down and stems grow up. 3. Thigmotropism-Response to touch. May be used for venus fly trap, to capture insects, or allow a plant to grow on a surface for support. Tendril