Flowering Plants: Structure and Organization

1. Flowering Plants: Structure and Organization Unit 10: Plants

2. Flowering plants usually have three vegetative organs: the roots, the stem and the leaves. • The roots are part of the root system; the stem and leaves are part of the shoot system. • Vegetative Organs are concerned with growth and nutrition. Basic Structure of Vascular Angiosperms

3. Vegetative Organs

4. The root system in the majority of plants is located underground. • The root system • Anchors the plant in the soil and gives it support. • Absorbs water and minerals from the soil for the entire plant. • The absorptive capacity of a root is dependent on its many branches, which all bear root hairs in a special zone near the tip. Roots

5. Roots • Produce hormones that stimulate growth of stems and coordinate their size with the size of the root. • Store products of photosynthesis. Roots

6. The shoot system of a plant is composed of the stem, branches and leaves. • Stem – the main axis of a plant, has a terminal bud that allows the stem to elongate and produce new leaves. • Stem • Supports leaves to expose them to sunlight. • Contains vascular tissue that transports water and minerals from the roots through the stem to the leaves and transports products of photosynthesis. Shoot System - Stems

7. Horizontal, underground stems are known as rhizomes. Rhizomes send out roots below and shoots above at nodes as it grows. Rhizomes allow plants to increase their territory. • Node: occurs where leaves are attached to the stem. • Stems: In some plants such as cactus, the stem is the primary photosynthetic organ. • The stem can also be a reservoir (succulent plants) and store water. • Some underground branches of a stem known as a tuber, store nutrients. Shoot System - Stem

8. Vascular Angiosperm

9. Leaves are specialized for gas exchange. • Leaves carry out most of the photosynthesis of a plant. Photosynthesis requires water, carbon dioxide and sunlight. • Leaves receive water from the root system by way of the stem. • Stems and leaves function together to bring about water transport from the roots. Vascular Angiosperms - Leaves

10. Plants that bear leaves the entire year are called evergreens. • Plants that lose their leaves every year are called deciduous. • The wide portion of a foliage leaf is called the blade. • The petiole is a stalk that attaches the blade to the stem. Leaves

11. Leaves – Petiole and Blade

12. Flowering plants are divided into two groups, depending on the number of cotyledons, or seed leaves in the embryonic plant. • Some have one cotyledon, and these plants are known as monocotyledons, or MONOCOTS. • Other embryos have two cotyledons, and these plants are known as eudicotyledons or EUDICOTS. (formerly known as dicots) Vascular Angiosperms: Monocot and Eudicot (Dicot)

13. Cotyledons of eudicots supply nutrients for seedlings, but the cotyledon of monocots acts as a transfer tissue, and the nutrients are derived from the endosperm before the true leaves begin photsynthesizing. Monocots vs. Eudicots (dicot)

14. Monocot vs. Eudicot

15. Eudicots- the primary root or main root grows straight down and remains the dominant root of the plant. • TAPROOT: is often fleshy and stores food. Carrots, beets, turnips and radishes have taproots. • Monocots – there is no single, main root, instead, there are a large number of slender roots. • Fibrous root system Monocot vs. Eudicot

16. Tap Root vs. Fibrous Root

17. MONOCOTS EUDICOTS • Some of our most significant food sources are monocots, including rice, wheat and corn. • Grasses, lilies, orchids and palm trees. • The eudicots are the larger group and include some of our most familiar flowering plants – from dandilions to oak trees. Monocot vs. Eudicot

18. 1. List the three vegetative organs in a plant and state their major functions. • 2. List significant differences between monocots and eudicots. Check Your Knowledge

19. A flowering plant has the ability to grow its entire life because it possesses meristematic (embryonic) tissue. • APICAL MERISTEMS are located at or near the tips of stems and roots, where they increase the length of these structures. • The increase in length is called primary growth. • Monocots have in addition to their meristems – a type of meristem called intercalary (to insert) meristem which allows them to grow lost parts. Intercalary meristems occur between mature tissues, and they account for why grass can so readily regrow after being grazed by a cow. Tissues of Flowering Plants

20. Flowering plants have apical meristem plus three types of primary meristem. • Protoderm produces epidermal tissue. • Epidermal tissue forms the outer protective covering of a plant. • In roots, epidermal cells bear root hairs; in the leaves, the epidermis contains guard cells. In a woody stem, epidermis is replaced by periderm. • PERIDERM: The majority component of periderm is boxlike cork cells. As cork cells mature, their walls become encrusted with suberin, a lipid material that is waterproof and chemically inert. Tissues of Flowering Plants

21. Types of Plant Tissues

22. Ground Meristem produces ground tissue. • Ground tissue fills the interior of a plant. • Ground tissue forms the bulk of a flowering plant and contains: • Parenchyma: thin-walled and capable of photosynthesis when they contain chloroplasts. • Collenchyma: cells have thicker cell walls for flexible support. • Schlerenchyma: cells are hollow, nonliving support cells with secondary walls fortified by lignin. Tissues of Flowering Plants: Ground Tissue

23. Ground Tissue - Parenchyma

24. Ground Tissue (in Stem)

25. Procambium produces vascular tissue. • Vascular tissue consists of xylem and phloem. Tissues of Flowering Plants

26. Procambium – Vascular Tissues

27. Xylem and Phloem are considered complex tissues because they are composed of two or more kinds of cells. • Xylem contains two types of conducting cells: tracheids and vessel elements, which are modified sclerenchyma cells. • Both types of conducting cells are hollow and nonliving. Vascular Tissue: Xylem and Phloem

28. Vascular Tissue: Xylem

29. The conducting cells of phloem are specialized parenchyma cells called sieve-tube members arranged to form a continuous sieve tube. • Sieve-tube members contain cytoplasm but no nuclei. • The term sieve refers to a cluster of pores in the end walls, which is known as a sieve plate. • Each sieve-tube member has a companion cell which does have a nucleus. The two are connected by numerous plasmodesmata, and the nucleus of the companion cell may control and maintain the life of both cells. Vascular Tissue - Phloem

30. The "Typical" Plant BodyThe Root System • Underground (usually) • Anchor the plant in the soil • Absorb water and nutrients • Conduct water and nutrients • Food Storage • The Shoot System Above ground (usually) • Elevates the plant above the soil • Many functions including: • photosynthesis • reproduction & dispersal • food and water conduction • Note: the shoot system includes the leaves and the reproductive organs, although these will be covered in more detail separately Vascular Tissue - Phloem

31. The companion cells are also believed to be involved in the transport function of phloem. Vascular Tissue

32. List three specialized tissues in a plant and the cells that make up these tissues. • 2. Compare the transport function of xylem and phloem. Check Your Knowledge