Knowledge and skills objectives:

1. Observe plants and describe their shapes and characteristics.

Process and method:

1, can use a variety of sensory observation, comparison, and master the method of comparison.

Emotions, attitudes and values:

1, realize the interest in exploring life.

2. Realize that there are many similarities and differences between plants.

Teaching preparation:

1. The teacher chooses an observation place on campus for students to observe. 2. Observe the recording paper.

Teaching suggestion: On the basis of understanding the basic characteristics of biology in the last class, this class guides students to learn about plants, an important part of the life world. The arrangement of this class always revolves around the shape of plants. Through the observation of plants from the whole to the part, the information about plant diversity and external morphology is obtained, which permeates the knowledge of six organs of green flowering plants and the relationship between plants and the environment. Based on the students' existing experience, the teaching activities focus students' thinking on "plants" and find a "growing point" for understanding the diversity of plants. The main activity of this class is to observe plants. What are the common characteristics of plants on the basis of observation?

Teaching process:

I. Understanding plants as a whole

1. Learn about campus plants observed by students in advance: Tell me about campus plants you know? You can say the name or describe the shape. )

Teacher-student communication.

2. Guide how to observe and put forward observation requirements: Next, we will go to the campus to observe these plants. Show me the form and explain the requirements.

I know the campus.

Plant names, growth environment and growth characteristics in the forest

(You can write or draw) Line up in height.

(from short to high)

……

3. Students observe on the spot, and the teacher gives guidance at any time.

4. report and exchange.

5. Summary: There are various external shapes of plants.

Second, from the local understanding of plants.

1, put forward the observation task: to observe the same parts of different plants, including bark, leaves and flowers.

2, explain how to observe the bark: touch it first, what do you feel? Expand the bark again and see if the expanded pattern is different.

3. Explain how to observe the leaves: How long do you see the leaves at a node of the branch? Draw it.

4. Explain how to observe flowers: compare the differences between the two flower shapes and draw them.

5. Teachers and students communicate after observation.

6. Ask and think: What are the similarities between the plants we observed?

(Focus on the structural characteristics of roots, stems, leaves, flowers, seeds, etc. , all need water, air, sunshine and other life needs, all need to grow and breathe ...)

Third, recognize plant diversity and classify plants.

1. Look at the textbook 17 and ask: Do you know these plants? What other plants do you know?

2. Talk: Let's classify and tell us how you want to classify.

References:

Plants are ...

Plants are autotrophs that can carry out photosynthesis, transform inorganic substances into organic substances and live independently.

Plants have obvious cell walls and nuclei, and the cell walls are composed of glucose polymer-cellulose.

Plants are usually inactive because they don't need to look for food. But because plants can't walk, a large part of them will become delicious in animals' mouths. Not only the protein and energy provided by plants since herbivores, but also carnivores indirectly depend on the energy provided by plants. It can be said that plants play a vital role in nature. Life is almost impossible without plants. Because plants can't walk, their changes are closely related to the surrounding environment, and their life cycle is synchronized with the four seasons. Plants resist winter or dry season by setting seeds and falling leaves. They also have many unique survival skills. For example, plants have meristems and cells are totipotent, which makes them have strong regeneration ability. Any single plant cell tissue will grow into a new plant with various cell types, which is incomparable to animals.

Most plants belong to angiosperms, which are flowering plants, including many kinds of trees.

Plant classification grade

There are 450,000 kinds of plants in the world, of which more than 200,000 belong to higher plants, and there are more than 30,000 kinds of higher plants in China. There are so many kinds that it's a mess for people who are not familiar with it. However, when we understand the classification level of plants, we will find that they actually belong to each other and are orderly. Every plant, whether higher or lower, seed plant or spore plant, can be found in a certain position as long as its scientific name is given.

Through hard work, plant taxonomists have generally figured out the relationship between various plants and arranged them into a system according to their genetic relationship, from low to high, from simple to complex. In this system, every plant has its own position, just like everyone has an account. This system consists of several levels, the level is "boundary", followed by "door", "class", "order", "family" and "genus", and the most basic level is "species". One or more species form a genus, one or more genera form a family, and so on, and finally several phylum form a boundary, that is, the plant kingdom.

On the classification level, "family" is an intermediate classification unit. In the process of identifying plants, if we can grasp the classification level of "families", it will play a role in outlining. As long as we can master the characteristics of 15 to 20 common families, it is even more powerful to identify plants.

In all plants, it can be divided into 12 families; All angiosperms can be divided into more than 300 families. There are 1 to hundreds of thousands of plant species in each family, and some even contain tens of thousands of plant species. For example, there are only 1 species of Ginkgo biloba, more than 3,300 species of Rosaceae and more than 7,000 species of Papilionaceae. No matter how many species there are in this family, the genetic relationship between these species is relatively close. So they have many similarities in morphology, especially in the structure of flowers. It is mentioned in the inflorescence that Compositae has flower heads and Umbelliferae has umbels. In addition, Oleaceae is woody, almost all leaves are opposite, Labiatae has a lip-shaped corolla, and almost all stems are square; The ten ampere family are all herbs with ten ampere-shaped corollas. The leaves of rutaceae plants have aromatic oil glands. ...

Higher plants and lower plants

All plants in the world can be divided into two categories: higher plants or lower plants. Higher plants or lower plants must be in one category.

Higher plants refer to more complex and advanced plants in form, structure and mode. For example, they generally have the differentiation of roots, stems and leaves, and the differentiation of various tissues and organs. In the mode of * *, sexual mode and asexual mode appear alternately from generation to generation. In addition, the key point is that they have an "embryonic" structure during individual development. Plants with these characteristics are called higher plants. All the flowering plants we see are higher plants. In addition, there are some non-flowering plants, such as bryophytes growing in humid environment and ferns in humid environment, which are also higher plants.

Lower plants are a kind of plants with simple morphology, structure and lifestyle, which are at a low level in the process of evolution. They generally have no differentiation of roots, stems and leaves, and the whole plant is leaflike or filamentous, and even a plant is only formed by single cells. Most of them live in water, such as unicellular Chlamydomonas living in fresh water. Because of their growth, the whole water surface can be green. There are laver and kelp that live in seawater. Some lower plants can carry out photosynthesis by themselves, such as the above; Some of them can't carry out photosynthesis by themselves and live a parasitic or saprophytic life, such as mushrooms and shiitake mushrooms.

Seed plants and spore plants

Among all plants, we can also divide them into two groups according to whether they can produce seeds or not. Any plant that can produce seeds is called a seed plant, and any plant that cannot produce seeds is called a spore plant. Apple, soybean, masson pine and ginkgo are all seed plants. Seeds in the apple core, beans in the pod, pine nuts of Pinus massoniana and ginkgo trees are all seeds. Mushrooms and shiitake mushrooms are spore plants. They can neither blossom nor seed. Under their umbrellas, countless tiny particles will be scattered, which are their spores. All seed plants belong to higher plants, but conversely, not all seed plants are in higher plants. In the lower groups of higher plants, they have no seed organs and only produce spores, but they also have the structure of embryos, so this kind of spore plants also belong to higher plants. For example, bryophytes in higher plants are spore plants, because they do not produce seeds, but they have the structure of embryos, while mushrooms and shiitake mushrooms have no embryos.

In the absence of seeds, it can be roughly decided according to the following aspects.

(1) Almost all trees, shrubs and vines are seed plants.

(2) No matter the size or height of a plant, anything that can blossom, whether it is brightly colored or not, is a seed plant.

(3) All that can bear fruit are seed plants.

(4) Plants with reticular six veins or parallel veins are basically seed plants.

Angiosperms and gymnosperms

Among all seed plants, they can be further divided into two categories, namely angiosperms and gymnosperms. The common feature of these two plants is that they both have the structure of seeds, but there are many important differences between them. The main difference is that the seeds of angiosperms are all born in the fruit, but when the fruit is ripe and cracked, its seeds are not exposed, such as apples and soybeans. On the other hand, progeny plants have no fruit structure. Its seeds are only covered with a layer of scales, and the seeds are not tightly wrapped. On the branches of Pinus massoniana, there will be many reddish-brown oval pine cones. Careful observation will reveal that it is composed of many wooden scales, covering each other. If you peel off the scales, you can see that there are two winged seeds under each scale. In some plants, such as ginkgo biloba, the seeds are not even covered with scales. The seeds were planted on a long stem and exposed from beginning to end. Plants with these characteristics are called plants.

The fundamental difference between angiosperms and gymnosperms lies in whether the seeds are covered with fruits. But when we check whether a plant belongs to an angiosperm or a daughter plant, we don't have to look at its seeds. We usually judge it from other characteristics. First of all, whether it is a herb or a woody plant. If it is a herb, it must be an angiosperm, because all plants are woody plants. If you meet woody plants, first look for flowers. Those with flowers are angiosperms, because * plants don't bloom. If you meet woody plants without flowers, you can look at the leaves. Except ginkgo biloba, leaves are usually narrow, needle-shaped, scale-shaped, strip-shaped, conical and so on. Although ginkgo leaves are wide, they can be easily identified by folded fan-shaped leaves and forked veins. Other plants have slightly wider leaves, but they are narrowly lanceolate. These plants with slightly wider leaves will not be mixed with angiosperms, because the veins of these plants are not obvious except the midvein, and the texture of the leaves is thicker. There are more than 200,000 species of seed plants in the world, most of which are angiosperms, and only a few are * * * plants, totaling more than 700 species.

Dicotyledons and monocotyledons

Among all angiosperms, they can be divided into two categories, organic dicotyledons and monocotyledons. Their fundamental difference lies in whether the embryo of the seed develops into two cotyledons or one cotyledon. Two cotyledons are called dicotyledonous plants and one cotyledon is called monocotyledonous plants. The former such as apples and soybeans; The latter are rice and corn. These two plants are easy to distinguish because they have some obvious differences in morphology. Dicotyledonous plants have basically straight roots and developed taproots; Many are woody plants, and their stems can be continuously thickened; Vein is reticular vein; The number of sepals and petals of a flower is 5 or 4, and if the petals are together, there are 5 or 4 lobes. The root system of monocotyledonous plants is basically fibrous root system, and the main roots are underdeveloped, mainly herbs and few woody plants. The stems usually cannot be thickened year by year, and the veins are parallel. The number of sepals and petals of flowers is usually three or multiples of three. Using the above differences, monocotyledons and dicotyledons can be easily distinguished.

Dicotyledonous plants account for 4/5 of the total angiosperms. Besides almost all trees, dicotyledonous plants also include many fruits, melons, fibers, oils and many vegetables. Monocotyledon plants have a large number of food crops, such as rice, corn, barley, wheat, sorghum and so on.

Plant classification

(A) according to the morphology of plant stems to classify

Trees 1

Woody plants with upright trunks and a height of more than 5 meters are called trees. Corresponding to the low shrubs, the tall trees you usually see are all arbors, such as kapok, pine, magnolia and birch. Trees are divided into deciduous trees and evergreen trees according to whether they shed leaves in winter or dry season.

2. Shrubs

Woody plants with inconspicuous trunk and many branches at the base are called shrubs, such as roses, dragonflies, azaleas and peonies.

Step 3: Shrub

It is a dwarf shrub, perennial, with herbs on the upper part of the stem, withered after flowering, and woody stems at the base, such as Catharanthus roseus and Cassia obtusifolia.

4. vanilla

The stems of herbaceous plants contain less woody cells, and the whole plant or aboveground parts are easy to wither or die, such as chrysanthemums, lilies and impatiens. Also divided into annual, biennial and perennial herbs.

5. Lianas

The stem is very long and can't stand upright. Plants that climb up by other things are called lianas. Lianas can be divided into woody vines and herbaceous vines according to the nature of stems, and common wisteria is woody herbs.

Lianas can be divided into climbing lianas according to whether they have special climbing organs, such as melons and peas, which have tendrils or adventitious air roots and can grow around other things; Twisted vines, such as morning glory and honeysuckle, can grow around other things.

(2) Classification according to the ecological habits of plants

1, terrestrial plants

Plants that grow on land.

2. Aquatic plants

Refers to plants whose plants are totally or partially submerged in water, such as lotus and water lily.

3. Epiphytes

Plants, such as most tropical orchids, are attached to other things, but they can survive independently without absorbing nutrients from their supporters.

4. Parasitic plants

Parasitic in the root of the host, using the nutrients and water of the host to live, such as Taxilli, Cuscuta, etc.

5. saprophytes

Plants without chloroplasts and leaves on their stems, such as fungi and crystal orchids.

(3) Classify plants according to their life cycle.

1, annual plant

The life cycle of this kind of plants is short, from a few weeks to several months, completing its life process within one year, and then the whole plant dies, such as cabbage and beans.

2. Biennial plants

Plants that germinate and grow in the first year and die after flowering and fruiting in the second year, such as sugar beet.

3. Perennial plants

The life cycle grows year after year, and many years, such as common trees and shrubs are perennial plants. In addition, there are some perennial herbs that can survive for many years, or the aboveground parts wither in winter and continue to grow, bloom and bear fruit in the next year.

Common evergreen and deciduous plants

1, conifer

(1) Evergreen conifers: such as cedar, Cryptomeria, Podocarpus, etc.

(2) Deciduous conifers: such as Pinus bungeana, Metasequoia glyptostroboides, Taxodium ascendens, Taxodium ascendens, Larix gmelinii, etc.

2. Broad-leaved trees

(1) Evergreen broad-leaved trees: such as Cinnamomum camphora, Magnolia grandiflora, Nanmu, etc.

(2) Deciduous broad-leaved trees: such as Pterocarya stenoptera, Platanus acerifolia, Paulownia, Sophora japonica, Ginkgo biloba, Populus tomentosa, etc.