Flowering Plants: Structure and Organization

2. Flowering Plants: Structure and Organization 10.1 Organs of Flowering Plants 10.2 Tissues of Flowering Plants

3. Flowering Plants: Structure and Organization • Over 80% of all living plants are flowering plants (angiosperms). • The organization of flowering plants allows them to grow on land. • The vegetative organs of a flowering plant consist of root, stems, and leaves. • The leaves shape facilitates absorption of solar energy and CO2. • Roots anchor the plant and also absorb water and minerals. • Strong stems conduct water up to the leaves from the roots

4. 10.1 Organs of Flowering Plants

5. Terminal bud Blade Vein Petiole Leaf • A plants possess two systems: • The root system (roots). • The shoot system (stem and leaves). • A typical plant have three vegetative organs which concerned with the growth and nutrition: (root, stemandleaves). • Also, a typical plant have reproductive organs which have specific function (reproduction): Flowers, seeds, andfruits Axillary bud Stem Node Internode Node Shoot system Root system Root branch Root hairs

6. 1- Roots system (The Root) • Roots (in the majority of plants) is located underground. • As a rule, the root system is extent to the shoot system. • Function of the roots • Anchors the plant in the soil • Gives it’s support • Absorbs water and minerals from the soil for the entire plant • Roots produce hormones that stimulate the growth of stems • Store the foods, (as in Carrots and sweet potatoes) • Suitability of the roots to their function • The cylindrical shape to penetrate the soil and to absorb water from all sides • Root hairs and branches: increase the absorptive capacity • Numerous root hairsincrease the absorptive surface of a root

8. The shoot system : 1- The stem • The shoot system of a plant is composed of the stem, branches and leaves. • Stem is the main axis of a plant • Terminal bud occur at the top of the stem that allows the stem to elongate and produce new leaves. • Anaxillary bud, located at a node in the upper angle between the leaf and the stem • Axillary bud can produce new branches of the stem (or flowers). • A nodeoccurs where leaves areattached to the stem. • The region between nodes is called an internode.

9. Branch Stem Leaf

10. 2- Leaves Leaves are the major part of a plant that carries on photosynthesis • Photosynthesis is a process that requires water, carbon dioxide, and sunlight. • The size, shape, color, and texture of leaves are highly variable. • The shape of leaves can vary from spines to deeply lobed. • Plants that bear leaves the entire year are called evergreens and those that lose their leaves every year are called deciduous.

11. The wide portion of the leaf is called the blade. • The petiole is a stalk that attaches the blade to the stem. • The upper acute angle between the petiole and stem is the leaf axil where the axillary bud is found.

12. Not all leaves are foliage leaves. • Some are specialized to protect buds, attach to objects (tendrils), store food (bulbs), or even capture insects.

13. Monocotyledons and Eudicotyledons • Flowering plants are divided into two groups, depending on the number of cotyledons, or seed leaves, in the embryonic plant. • Monocotyledons (Monocots): have one cotyledon. • Eudicotyledons (Eeudicots): have two cotyledons. • Cotyledons of eudicots supply nutrients for seedlings, but in monocots acts as a transfer tissue and the nutrients are derived from the endosperm . • In the monocot root vascular tissues occurs in a ring. • In the eudicot root, the xylem is star-shaped and the phloem is located between the points of the star. • Leaf veins are vascular bundles within a leaf. • Leaf veins in Monocots exhibit parallel venation, but in eudicots exhibit netted venation, which may be either pinnate or palmate. • Monocots have their flower parts arranged in multiples of three, and eudicots have their flower parts arranged in multiples of four or five.

14. Seed Root Stem Leaf Flower Monocot Vascular bundles scattered in stem Leaf veins parallel Flower parts 3 or multiple One cotyledon in seed Xylem and phloem in ring Dicot Phloem between arms of xylem Vascular bundles in a distinct ring Flower parts 4 or 5 or multiple Leaf veins in net Two cotyledon in seed

15. 10.2 Tissues of Flowering Plants

16. A flowering plant has the ability to grow because it possesses meristematic (embryonic) tissue. • Apicalmeristemsare located at or near the tips of stems and roots. • Apicalmeristemsincrease the length of the plants. • Apical meristem continually produces three types of meristem: • Protoderm which gives rise to epidermis (forms the outer protective covering of a plant) • Ground meristem produces ground tissue (fills the interior of a plant) • Procambium produces vascular tissue (transports water and nutrients in a plant and provides support.

17. Epidermal Tissue • The entire body of both non-woody (herbaceous) and young woody plants is covered by a layer of epidermis. • The walls of epidermal cells that are exposed to air are covered with a waxy cuticle for prevent water loss and protects the plants against bacteria and other organisms that might cause disease. • In roots, certain epidermal cells have long, slender projections called root hairs, to increase the surface area of the root for absorption of water and minerals; they also help anchor the plant firmly in place. • On stems, leaves, and reproductive organs, epidermal cells produce hairs called trichomes. • In leaves, the lower epidermis of eudicots and both surfaces of monocots contain specialized cells called guard cells (epidermal cells) with chloroplasts.

18. Ground Tissue • Ground tissue forms the bulk of a flowering plant and contains parenchyma, collenchyma, and sclerenchyma cells • Parenchyma • Parenchyma cells are the most abundant tissues in the plant organs. • They may contain chloroplasts and carry on photosynthesis

19. Collenchyma • Collenchyma cells are like parenchyma cells except they have thicker primary walls. • The thickness is uneven and usually involves the corners of the cell. • Collenchyma cells give flexible support to immature regions of a plant body.

20. fiber Sclerenchyma • Sclerenchyma cells have thick secondary cell walls of lignin, that makes the walls tough and hard. • Most sclerenchyma cells are nonliving • Their primary function is to support the mature regions of a plant. • Two types of sclerenchyma cells are fibers and sclereids. • Althoughfibers are occasionally found in ground tissue, most are in vascular tissue. • Fibers are sometimes commercially important. • Sclereids are shorter than fibers and are found in seed coats and nutshells. • The hardness of nuts and peach pits is due to sclereids. sclereids

21. Vascular Tissue • There are two types of vascular (transport) tissue: • Xylemtransports water and minerals from the roots to the leaves. • phloemtransports sucrose and other organic compounds, including hormones, usually from the leaves to the roots. • Both xylem and phloem are considered complex tissues because they are composed of two or more kinds of cells. • Xylem • Xylem contains two types of conducting cells: • Tracheids and vessel elements (VE), which are modified sclerenchyma cells. Both cells are hollow and nonliving. • But the vessel elements are larger, may have perforation plates in their end walls, and are arranged to form a continuous vessel for water and mineral transport.

22. vessel element vessel element tracheids perforation plate Pitted walls tracheids xylem parenchyma pits a. Xylem micrograph (left) and drawing (to side) b. Two types of vessels c. Tracheids Xylem structure a. Photomicrograph of xylem vascular tissue and drawing showing general organization of xylem tissue. b. Drawing of two types of vessels (composed of vessel elements)—the perforation plates differ. c. Drawing of tracheids.

23. Phloem: • The conducting cells of phloem are specialized parenchyma cells called sieve-tube members which arranged to form a continuous sieve tube. • Sieve-tube members contain cytoplasm but no nuclei. • Each sieve-tube member has a companion cell, which does have a nucleus. • The companion cells are believed to be involved in the transport function of phloem. • Sclerenchyma fibers also lend support to phloem. • In the roots, the vascular tissue is located in the vascular cylinder; • In the stem,it forms vascular bundles; • In the leaves, it is found in leaf veins.

24. sieve plate sieve-tube member sieve-tube member companion cell companion cell sieve plate nucleus phloem parenchyma a. Phloem micrograph (left) and drawing (to side) b. Sieve-tube member and companion cells Phloem structure a. Photomicrograph of phloem vascular tissue and drawing showing general organization of phloem tissue. b. Drawing of sieve tube (composed of sieve-tube members) and companion cells