Chapter 22 The Plant Kingdom

1. Chapter 22The Plant Kingdom

2. Plants • What are plants? • Eukaryotic, multicellular organisms that have chlorophyll and carry out photosynthesis • For the most part, they are terrestrial • Live in almost all types of environment • Can be big, or can be small • Remember, they are autotrophic!

3. Plants are Invading the Land! • About 500 million years ago, a group of green algae developed adaptations that enabled them to invade the land. • Over 85% of land plants are flowering plants, the Angiosperms. • 14% are mosses and ferns. • 1% are conebearing plants (Gymnosperms). • The challenges to invading the land include: • preventing water loss • absorbing and transporting water • fertilization and protection of the embryo • Structural support

5. Alternation of Generations • Plants have a life cycle that involves two distinctly different generations • Sporophyte generation is diplod (2N) and has plant parts in which meiosis can take place to be haploid • Gametophyte generation is haploid (N) and develops structures that produce gametes • The gametes will be produced through mitosis • When two haploid gametes unite a diploid zygote is formed

6. Nonvascular Plants • Nonvascular plants include mosses, hornworts, and liverworts, and are commonly known as bryophytes • They all have these following characteristics • They lack vascular tissue • They do not have true roots or leaves • The gametophyte generation is the most prominent part of the life cycle • Sperm swim to the egg

7. Moss Life Cycle • The moss plant you generally see is the gametophyte generation • Two structures that produce gametes • Antheridium is made up of a jacket of cells surrounding the developing sperm • Archegonium is a flask shaped structure that produces the egg • When sperm mature, antheridian opens and sperm will swim through a film of dew or rainwater to archegonium • Sperm and egg nuclei fuse, diploid zygote is produced and is in the sporophyte generation

8. Vascular Tissue • Plants, excluding the bryophytes have a vascular system to transport water and nutrients throughout the plant • Roots are underground structures that anchor the plant and absorb water and minerals • Leaves are structures specialized for carrying out photosynthesis • Stems are structures which connect the roots with the leaves and position the leaves so they receive sunlight

9. Vascular Tissue • Two kinds of vascular tissue: xylem and phloem • Xylem consists of a series of dead, hollow cells arranged end to end to to form a tube • Carries water and minerals up from the roots through the stem to the leaves • Phloem carries organic molecules (sugars, aa) produced in the leaves to other parts of the plant where growth takes place

10. Roots • Roots never stop growing by their tips to try and get new territory for available nutrients and water • Most roots are storage places for the food produced by the plant to store during harsher seasons • Some roots are a source of food for us, such as carrot, turnips, and radishes

11. Stems • Two basic functions of stems: • Support the leaves • Transport raw materials from root to leaves and food from leaves to roots • Inside the bark here are seven layers of xylem tissue. Each layer of xylem constitutes 1 years tree growth

12. Leaves • Leaves carry out photosynthesis • Have a large surface area to try to collect as much sunlight as possible • Stomates open and close to control the rate at which water is lost and gases are exchanged • During times of drought, the stomates are closed to reduce the rate at which the plant loses water

13. Seedless Vascular Plants • Seedless vascular plants include whisk ferns, horsetails, club mosses and ferns • They have vascular tissue, but do not produce seeds • Not as limited to wet areas as nonvascular plants, because they have roots and vascular tissue. • Still need water to move sperm

14. Ferns • Most abundant of the seedless vascular plants • Found in greater number in the tropics, but can be found throughout the world • Some are very small, while some can grow to be very large. • Some have trunks which are 79 feet high, and leaves that grow up to 16 feet long • The stage you see when looking at ferns are mostly sporophytes • The vertical leaves on ferns are known as fronds • On the underside of the fronds, the spore producing parts are located, known as sori (sorus)

15. Fern Life Cycle

16. Seed-Producing Vascular Plants • Seed is a specialized structure that contain an embryo, along with stored foot, enclosed in a protective coat, known as a seed coat • Two major groups of plants that produce seeds: • Gymnosperms (conifers) • Angiosperms (flowering plants)

17. Gymnosperms • Gymnosperms (naked seed plants) are plants that have cones (woody structures) where their seeds are produced. • Pollen grains are the male gametophytes, and the transfer of pollen is known as pollination.

18. Gymnosperm Life Cycle

19. Types of Gymnosperms • Cyads – are stout, woody gymnosperms that have a ring of fernlike leaves on the top that live in tropical regions. • Ginkgo trees- have fan-shaped leaves. There is only one species left, Ginkgo biloba. Reproductive strucutres of ginkgos are on separate trees.

20. Types of Gymnosperms • Conifers are the common trees and shrubs that bear seeds in cones and many have needle-shaped leaves.

21. Angiosperms • Angiosperms are plants that produce flowers and have their seeds enclosed in fruit. • Fruit is a modification of the ovary wall into a special structure that contains the seeds. • Flower is the structure, composed of highly modified leaves, that is responsible for sexual reproduction.

22. Flower Structure • Pistil is at the center of a flower, which is composed of the stigma, style and ovary. • Stigma is the terminal portion of the pistil and is meant to receive pollen. • Style is where the male gamete travels down into the ovary • Ovary is the female reproductive structure • Stamen is male organ of a flower • Filament is the stalk of the anther • Anther contains pollen sacs. The sacs release pollen on to the outside of the anthers that brush against insects on entering the flowers.

23. Flower Structure