Reporters: VIANCA PAMELA DELOS REYES JESTER CRUZ
CHAPTER 12: FLOWERING PLANTS
In this chapter, you will study the structure of flowering plants, how they function, and how they respond to the environment.

1. FLOWERS, SEEDS, and FRUITS
-Some flowers are large and showy. Some are small. Even though flowers look different, they have the SAME FUNCTIONS. Flowers are the structures of sexual reproduction in angiosperms.

RECEPTACLE-enlarged end of the stem under the flower.
SEPALS-Circle of green leaf-like parts found around the bottom of the flower. They cover and protect the developing bud.
PETALS-is found inside the sepals. These are usually the bright colored parts you see in flowers. Petals surround the reproductive parts of the flower.
STAMENS-slender structures with knobs on top are near the middle of the flower.
The slender parts are the FILAMENTS and the knobs are the ANTHERS.

The tall, vase like part in the middle of the flower are called the PISTIL. Notice the sticky stigma is supported by the STYLE. At the base of the pistil is the OVARY. Inside the ovary are one or more ovules. An egg is produced inside each ovule.

PERFECT FLOWERS-have both stamens and a pistil.
IMPERFECT FLOWERS-have either stamens or a pistil, but not both.

HOW SEEDS AND FRUITS DEVELOP

For seeds to form in Angiosperms, a pollen grain should be transferred from an Anther to a Stigma. Stigma helps trap the pollen. Recall chapter 11.

When a seed begins to form, a flower changes in many ways. The flower’s petals and stamens wither and fall off.
SEED COAT-it protects the embryo from drying out.

As a seed develops, the ovary ripens and develops into a fruit. Sometimes, a part of the receptacle or the sepals also become part of the fruit. Depending on the type of plant, some ripened ovaries can be moist and fleshy, while others are dry and hard.
(e.g.: Pea pods and peanut shells.)

A fruit can develop from one or more ovaries.
SIMPLE FRUITS- are developed from a single ovary that may have one or more ovules.
(e.g.: Papayas, watermelons, melons, and bananas.)
COMPOUND FRUITS-are developed from more than one ovary. Some fruits such as ATIS, develop from many ovaries of the same flower. Other, such as PINEAPPLES, develop from many ovaries in a cluster of flowers.

2. VEGETATIVE REPRODUCTION

Natural Vegetative Reproduction

Some angiosperms can reproduce asexually from their roots, stems, or leaves. These plants are vegetative because they do not produce reproductive structures such as seeds.

VEGETATIV E REPRODUCTION-the asexual reproduction of new plants from roots, stem or leaves.

Example:

KALANCHOE- reproduces vegetatively from LEAVES.

ONIONS- reproduce vegetatively from STEMS.

* BULB-is a modified shoot composed of overlapping fleshy scale leaves. * STEM-is located at the basal portion of the bulb.

TAKIP-KOHOL- (Hydrocolyte) reproduce by means of a runner called STOLON.

* A RUNNER is a modified stem that grows across the top of the soil. New plants grow at certain points where the runner touches the ground.

ARTIFICIAL VEGETATIVE REPRODUCTION Methods of Artificial vegetative reproduction—LAYERING, CUTTING, and GRAFTING 1. LAYERING-they cover with soil a branch that has one or more buds. Each bud grows into a new plant and can be cut away. (e.g.:Rose bushes and some kind of ferns reproduced by layering.) 2. CUTTINGS-are stems, roots or leaves that are cut-off from a plant and place in water, sand or soil. The cuttings grow and develop into whole plants. (e.g.: Bougainvilleas, African Violets, Begonias, and Coleus.) 3. GRAFTING-cutting off a piece from the top of a plant and attach it to the root system or stem of another plant. It involves joining hardier parts of one plant to another plant. (e.g.: Fruit trees like mangoes and rambutan.)

3. ROOTS and STEMS: Support and Transport Structure and Function of Roots * Roots of some plants store food. * Plant makes more sugar than it can use. * Excess sugar is changed into starch and then stored in the plant’s roots. * When the plant needs sugar, the starch changed back into sugar. * Roots obtain water and minerals from the soil. * Water and minerals are absorbed through the roots and travel up the stems and leaves. * Fuzzy structures on the young plant are root hairs. * The root hairs are extensions of the epidermal layer of root cells. * Minerals, such as potassium, nitrogen, and calcium move into the root hairs by active transport. DICOTS-have a long, slender root called TAPROOT. This kind of root can reach water deep inside the ground. These roots help anchor the plant in the soil. MONOCOTS-plants have branching roots called FIBROUS ROOTS. Fibrous roots do not grow as deep as taproots. They spread out over a wide area near the surface of the soil. CROSS-SECTION OF A ROOT EPIDERMIA-A single outer layer of cells protects the root. It is also the layer where root hairs develop. CORTEX-It is composed of thin walled cells known as PARENCHYMA. PARENCHYMA-are cells that store starch. In the center of the root is the vascular tissue. It is made up of two kinds of cells: XYLEM and PHLOEM. XYLEM-cells are thick-walled cells are connected end-to-end, forming long continuous tubes. Water and Minerals move up through the Xylem. PHLOEM-a living and thin-walled cells. They are also connected from end-to-end and form continuous tubes. Sugar moves up and down through Phloem. PITH-composed of parenchyma cells occupy the center. The vascular tissues are scattered at the outer layer of the pith near the cortex. SCLERENCHYMA-are dead cells. It is a cell which helps in making the roots strong for anchorage of the plants. COLLENCHYMA-Those are dead cells with thick walls.

Structure and Function of Stems * Produces and supports the leaves and the reproductive parts such as cones and flowers. MERISTEMS-are group of cells. It is localized region of cell division which is the growth points of the plants. WOODY STEMS-Stems that is rigid and hard. Trees and shrubs have woody stems and grow for many years. CROSS-SECTION OF A STEM SCLERENCHYMA-are dead cells. It is a cell which helps in making the roots strong for anchorage of the plants. COLLENCHYMA-Those are dead cells with thick walls. 4. LEAVES: Organs of Photosynthesis Leaves are the special organs of a plant that trap the sun’s energy and use the energy to make sugar. Although leaves have the same function, they vary in shapes and sizes. * Flat wide part of the leaf is called the BLADE. * Angiosperms have broad leaves. * Leaves that have stem-like part are called PETIOLE. * EPIDERMIS which makes up the upper and lower layers. These layers protect the inner cells of the leaf. * CUTICLE-reduces water loss from leaf. * PALISADE LAYER-The long, sausage-shaped cells just below the upper epidermis. * SPONGY LAYER-This is beneath the palisade layer. Irregular shaped cells. * Gases that pass through tiny openings are called STOMATA. * TRANSPIRATION-is a process which plants lose water through the Stomata. * PHOTOSYNTHESIS-process takes place in the chloroplasts where the chlorophyll molecules are found. PROCESS OF PHOTOSYNTHESIS: Carbon Dioxide + Water Glucose + Oxygen CELLULAR RESPIRATION: Glucose + Oxygen Carbon Dioxide + Water + Energy

5. PLANT TROPISMS TROPISMS * Growth movement of plant towards or away from the stimulus is known as TROPISM. * Growth response to light is called PHOTOTROPISM. * Response of stems and roots to gravity is called GRAVITROPISM. * THIGMOTROPISM-is a third kind of tropism. It growth response to touch.

AUXINS * Are one group of plant hormones. Auxins increase growth by causing individual cells to become longer. How Leaves Respond to the Environment * Changing Colors and Falling to the Ground.