Table of Contents Chapter: Plants Section 1: An Overview of Plants Section 2: Seedless Plants Section 3: Seed Plants
An Overview of Plants • Plants are important food sources to humans and other consumers. 1 What is a plant? • Between 260,000 and 300,000 plant species have been discovered and identified. • Without plants, most life on Earth as we know it would not be possible.
An Overview of Plants 1 Plant Characteristics • Plants range in size from microscopic water ferns to giant sequoia trees that are sometimes more than 100 m in height. • Most have roots or rootlike structures.
An Overview of Plants 1 Plant Characteristics • Plants are adapted to nearly every environment on Earth. • All plants need water.
An Overview of Plants 1 Plant Cells • A plant cell has a cell membrane, a nucleus, and other organelles. • In addition, plant cells have cell walls that provide structure and protection.
An Overview of Plants 1 Plant Cells • Most plant cells contain the green pigment chlorophyll, so most plants are green. • Chlorophyll is found in a cell structure called a chloroplast.
An Overview of Plants • Most plant cells have a large, membrane-bound structure called the central vacuole that takes up most of the space inside of the cell. 1 Plant Cells • This structure plays an important role in regulating the water content of the cell.
An Overview of Plants 1 Comparing Plants to Algae • Algae can survive only in damp areas. Why? (p.364) • How does the structure of plants allow them to live in dry areas?
An Overview of Plants 1 Comparing Plants to Algae • Plants and green algae have the same types of chlorophyll and carotenoids in their cells. • Does this mean that plants and green algae have a common ancestor?
An Overview of Plants 1 Fossil Record • Most animals have bones or other hard parts that can fossilize. • Plants usually decay before they become fossilized.
An Overview of Plants 1 Fossil Record • However, we have found some fossilized plants. • To form fossils, you need… • Quick burial. • Water, in the right amounts. • Suitable minerals. • …so, conditions during the Genesis flood were ideal for “fossilizing” millions of animals and plants.
An Overview of Plants 1 Plant Structure • More sunlight and carbon dioxide—needed for photosynthesis—are available on land than in water. (where do you find plants?) • During photosynthesis, plants give off oxygen.
An Overview of Plants • Covering the stems, leaves, and flowers of many plants is a cuticle, a waxy, protective layer secreted by cells onto the surface of the plant. 1 Plant Structure: Protection and Support • The cuticle slows the loss of water.
An Overview of Plants 1 Plant Structure: Protection and Support • Like all cells, plants cells have cell membranes, but they also have rigid cell walls outside the membrane. • Long chains of cellulose molecules form tangled fibers in plant cell walls. These fibers provide structure and support.
An Overview of Plants 1 Other Cell Wall Substances • Cells of some plants secrete other substances into the cellulose that make the cell wall even stronger. • Trees, such as oaks and pines, could not grow without these strong cell walls.
An Overview of Plants 1 Vascular tissue • Many plants have structures that distribute water, nutrients, and food to all plant cells.
An Overview of Plants 1 Reproduction • Some plants reproduce through water-resistant spores • Other plants produce water-resistant seeds in cones or in flowers that develop into fruits.
An Overview of Plants 1 Classification of Plants • Scientists group plants into 2 major groups: • vascular or nonvascular plants.
An Overview of Plants 1 Classification of Plants • Vascular plants have tubelike structures that carry water, nutrients, and other substances throughout the plant. • Nonvascular plants do not have these tubelike structures and use other ways to move water and substances.
Section Check 1 Question 1 Why are most plants green? Answer Most plants contain the green pigment chlorophyll. Plants need chlorophyll to make food using the process of photosynthesis. NC: 4.03
Section Check 1 Question 2 Plants and green ______use the same pigments for photosynthesis. A. algae B. fungi C. sponges D. viruses NC: 4.03
Section Check 1 Answer The correct answer is A. Both plants and green algae have the same types of chlorophyll and carotenoids in their cells. Carotenoids are red, yellow, or orange pigments. NC: 4.03
Section Check 1 Question 3 Why might you expect a plant living on land to use photosynthesis more efficiently than an aquatic plant? Answer More sunlight and carbon dioxide are available on land. Both of these are needed for photosynthesis. NC: 7.02
Seedless Plants 2 Seedless Nonvascular Plants • Nonvascular plants are usually just a few cells thick and only 2 cm to 5 cm in height. • Instead of roots, threadlike structures called rhizoids (RI zoydz) anchor them where they grow.
Seedless Plants 2 Seedless Nonvascular Plants • Most nonvascular plants grow in places that are damp.
Seedless Plants 2 Seedless Nonvascular Plants • Water is absorbed and distributed directly through their cell membranes and cell walls. • Nonvascular plants also do not have flowers or cones that produce seed. • They reproduce by spores.
Seedless Plants 2 Mosses • Mosses have green, leaflike growths arranged around a central stalk. • Sometimes stalks with caps grow from moss plants. • Reproductive cells called spores are produced in the caps of these stalks.
Seedless Plants 2 Liverworts • In the ninth century, liverworts were thought to be useful in treating diseases of the liver. • Liverworts are rootless plants with flattened, leaflike bodies. • They usually have one-celled rhizoids.
Seedless Plants 2 Hornworts • Most hornworts are less than 2.5 cm in diameter and have a flattened body like liverworts. • Almost all hornworts have only one chloroplast in each of their cells. • Hornworts get their name from their spore-producing structures, which look like tiny horns of cattle.
Seedless Plants 2 Nonvascular Plants and the Environment • Mosses and liverworts are important in the ecology of many areas. • They can grow in thin soil and in soils where other plants could not grow. • Spores of mosses and liverworts are carried by the wind.
Seedless Plants 2 Nonvascular Plants and the Environment • Mosses often are among the first plants to grow in new or disturbed environments, such as lava fields or after a forest fire. • Organisms that are the first to grow in new or disturbed areas are called pioneerspecies.
Seedless Plants 2 Nonvascular Plants and the Environment • As pioneer plants grow and die, decaying material builds up. • North Face Of Piatra Craiului Mountains • This, along with the slow break-down of rocks, builds soil.
Seedless Plants 2 Seedless Vascular Plants • Ferns and mosses are alike in one way. • Both reproduce by spores instead of seeds. However, ferns are different from mosses because they have vascular tissue.
Seedless Plants 2 Seedless Vascular Plants • The vascular tissue is made up of long, tubelike cells. • These cells carry water, minerals, and food to cells throughout the plant. • Vascular plants can grow bigger and thicker because the vascular tissue distributes water and nutrients to all plants cells.
Seedless Plants 2 Types of Seedless Vascular Plants • Besides ferns, seedless vascular plants include ground pines, spike mosses, and horsetails. • Ferns are more abundant, with at least 12,000 known species.
Seedless Plants 2 Ferns • The largest group of seedless vascular plants is the ferns. • They have stems, leaves, and roots. • Fern leaves are called fronds. • Ferns produce spores in structures that usually are found on the underside of their fronds.
Seedless Plants 2 Ferns • Fern spores
Seedless Plants 2 Club Mosses • Ground pines and spike mosses are groups of plants that often are called club mosses. • These seedless vascular plants have needle-like leaves.
Seedless Plants 2 Club Mosses • Spores are produced at the end of the stems in structures that look like tiny pine cones.
Seedless Plants 2 Horsetails • The stem structure of horsetails is unique among the vascular plants. • The stem is jointed and has a hollow center surrounded by a ring of vascular tissue.
Section Check 2 Question 1 Sometimes stalks with caps grow from moss plants. What is the importance of these stalks? Answer The stalks are reproductive structures of the moss plant. Reproductive cells called spores are produced in the caps of these stalks.
Section Check 2 Question 2 How are ferns different from mosses? A. they are seedless B. they are vascular C. they contain chlorophyll D. they produce spores NC: 7.02
Section Check 2 Answer The correct answer is B. All of the other characteristics are shared by ferns and mosses. Because ferns have vascular tissue and mosses do not, ferns can grow to be much larger than mosses. NC: 7.02
Section Check 2 Question 3 Submerge seedless plants in water and mud. Do not let them decay. Continue to add layers and let them compact and compress. These statements are a “recipe” for making what? NC: 4.04
Section Check 2 Answer This is a recipe for making coal. Today a similar process is taking place in bogs. When plants die in bogs, the waterlogged soil slows decay. Over time, the plants are compressed into a substance called peat. NC: 4.04
Seed Plants 3 Characteristics of Seed Plants • Most seed plants have leaves, stems, roots, and vascular tissue. • They also produce seeds, which usually contain an embryo and stored food. • The seed plants generally are classified into two major groups—gymnosperms (JIHM nuh spurmz) and angiosperms (AN jee uh spurmz).
Seed Plants 3 Gymnosperms • Gymnospermsare vascular plants that produce seeds that are not protected by fruit.
Seed Plants 3 Gymnosperms • Another characteristic of gymnosperms is that they do not have flowers. • Leaves of most gymnosperms are needlelike or scalelike.
Seed Plants 3 Gymnosperms • Four divisions of plants—conifers, cycads, ginkgoes, and gnetophytes(NE tuh fites)—are classified as gymnosperms. • You are probably most familiar with the division Coniferophyta (kuh NIH fur uh fi tuh), the conifers. • Pines, firs, spruces, redwoods, and junipers belong to this division.