THE PLANT THE PLANT KINGDOM & THEIR KINGDOM & THEIR

STRUCTURESSTRUCTURES

Chapter 12

PLANT PLANT CLASSIFICATIONCLASSIFICATION

Botony, the study of plants, may not top your list of interesting subjects.

• First, not all green things are plants. Fungi can contain green pigments. Algae, protozoans, and even some bacteria may contain enough chlorophyll to make them green.

• Second, not all plants are green. Some have other pigments which mask the green chlorophyll. Although most plants carry on photosynthesis with chlorophyll localized in plastids (autotrophic), there are thousands of heterotrophic plants. What is the difference between autotrophic and heterotrophic again?

• Third, we cannot overestimate the value of plants to man. The plant kingdom provides almost all our food.

• Last, plants are a source of inestimable beauty. The quiet of a lush forest and the delicacy of a soft flower demonstrate much of God’s plan and creation.

Importance of plantsImportance of plants• Without plants life on earth would not exist

Plants:Plants:•Primary source of

food for people and animals

•Produce oxygen

•help to keep us cool

•renew the air

Plants:Plants:•slow wind speed

•provide a home for wildlife

•beautify surroundings

•perfume the air

•furnish building materials and fuel

Main Groupings of Main Groupings of PlantsPlants

• Non-vascular plants: only one phylum of plants lacks vascular tissues. In this group are the mosses and similar plants.

• Vascular plants without seeds: Four phyla of plants have vascular tissues but lack seeds. The best known phylum is Pterophyta, the ferns.

• Vascular plants with seeds: This group is usually divided into the two following subgroups: flowering and non-flowering plants.

Non-Vascular Plants: The Non-Vascular Plants: The MossesMosses• Non-vascular plants are in phylum Bryophyta which

contains the mosses, liverworts, and a few similar groups.

• People often think any small green thing is a moss, even though it could be grass, fungus, or anything else.

• Most appear as velvety clumps in shaded areas.

• In a clump there actually are many densely packed individual plants.

• The most obvious part of a moss, the leafy shoot, is 1 in long and transmits water in small spaces between the cells in much the same way that a paper towel absorbs water.

• On the bottom of each shoot is a tangles mass of rhizoids. They may appear rootlike, but they lack conducting tissues and therefore are not true roots.

Vascular Plants Vascular Plants Without SeedsWithout Seeds

• All plants other than bryophytes have vascular tissues which conduct water and dissolved minerals through this plant

• They are unusual in that they do not produce seeds. In their life cycle they produce spores, a single cell with a protective coat, which are used to spread the species.

• When released, the powdery fern spores can be carried by the wind.

• Under proper conditions fern spores germinate and form a heart-shaped prothallus which is one cell layer thick.

Vascular Plants with Vascular Plants with SeedsSeeds

• Divided into two groups: gymnosperms (three phyla) & angiosperms (one phylum).

ConifersConifers

• Produce seeds in cones.

• Largest phylum of gymnosperms

• Not all cones are like the familiar pine cones and not all conifers look like pine trees, but the life cycle of a pine tree is typical.

• In spring, pine trees produce two types of cones: pollen cones and seed cones

• Pollen cones: short-lived, numerous, and small are found near the tips of branches. They contain the male reproductive gametes.

• Pollen lands on the open scales of the small, green, upright seed cone. Usually found on other branches of the same tree.

• The scales close tightly, and in many pines the cones begins to point downward.

• May not be fertilized until months later, and in some species they may not develop into seeds for several years.

• When the timing is right and seeds are mature, the scales open and release the seeds.

Angiosperms: Kingdom Angiosperms: Kingdom Anthophyta: Flowering Anthophyta: Flowering

PlantsPlants• Dominant vegetation on earth today

• So much diversity among the 250,000 species that they are grouped into nearly 400 different families, based primarily on floral parts.

• All angiosperms have seeds enclosed in an ovary and flowers.

• Many angiosperms do not produce colorful blossoms. Corn tassels and the catkins of oak trees are flowers.

AngiospermsAngiosperms• Divided into two classes: monocots & dicots

• The basic distinction between these two is the number of cotyledons

• The cotyledons has stored food to keep the embryonic plant alive while it is in the seed and to supply the sprout with energy until it can carry on photosynthesis.

• The ovary of a plant is the structure which encloses the seeds; a mature ovary is a fruit. You can easily identify apples, cherries, and tomatoes as fruits, but pods of peas and kernels of corn and wheat are also fruits.

PartParts of s of a a

planplantt• Four basic parts

• leaves

• stems

• roots

• flowers Leaves

Stems

Roots

Flowers

Let’s Look at a Plant…

flower

leaf

stem What important

part cannot be

seen?

Did you say “Roots”?

What’s the job of the roots?• They hold the plant in place.• They take in water from the soil.• They take in food from the soil.

What does the stem do?

The stem’s jobs:

• The stem stands the plant up.

• The stem is the elevator that takes the food and water to the rest of the plant.

Why do plants have leaves?

The leaf’s job:• The leaf breathes in air called carbon dioxide and breathes out oxygen.• The leaf takes in energy from the sun and turns it into energy for theplant.

This is called photosynthesis.

The Flower

• The flower attracts insects by its color and smell so insects can pollinate the flower.

• After being pollinated, the flower makes the seeds.

What does the flower do?

Leaf•Important function-manufactures

food for the plant by using light energy

•Can turn to catch the sunlight

Leaf Margin•Plants may be identified by the edges, shape, and arrangement of the leaves.

•The leaf edges are known as the margin

•A simple leaf is a single leaf arising from a stem

•Two or more leaves arising from a common point on the stem is a compound leaf

•A leaf consists of two familiar parts: petiole and blade

•The petiole is the stem of the leaf

•The blade is the wide portion

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• Almost all plants are photosynthetic autotrophs, as are some bacteria and protists

– Autotrophs generate their own organic matter through photosynthesis

– Sunlight energy is transformed to energy stored in the form of chemical bonds

(a) Mosses, ferns, andflowering plants

(b) Kelp

(c) Euglena

(d) Cyanobacteria

THE BASICS OF PHOTOSYNTHESIS

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• Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water

AN OVERVIEW OF PHOTOSYNTHESIS

Carbondioxide

Water Glucose Oxygengas

PHOTOSYNTHESIS

Leaf Structure

phloem (sugar)xylem (water)

stomate

palisadeslayer

spongylayer

cuticleepidermis

guardcells

cuticleepidermis

vascular bundle (vein)

Copy this to turn in and use

Roots•Roots can go down 6, 8, 10 feet

•Not all roots are below ground

•Most roots serve to anchor the plants

•They absorb water

•Transport these absorbed substances to where they are needed in plants.

•Also function as food storage as with carrots, radishes, and beets.

Notice how the growing zone has no root hairs or lateral roots!

Growth among soil particles would result in shear forces.

Zone of Maturation - cell differentiation

ProtodermGround MeristemProvascular

Zone of Cell Elongation - cell expansion

Zone of Cell Division - new cells by mitosis

Root Cap - penetration, padding

Roots• Plants such as Poison Ivy and English Ivy have

roots that help them climb trees, walls and sides of buildings

• These are called adventitious roots which appear where roots are not normally expected.

Roots Notes•Taproot is the main root of a plant and

generally grows straight down from the stem

Roots Notes•Fibrous roots are generally thin,

somewhat hairlike, and numerous. The Fibrous root system is normally shallow.

In shrubs like this tea plant (Camellia sinensis), the root system will be more tap root than fibrous root.

Notice the diameter of this tap root compared to this man’s waist!

But shrubs also generally have some compromise for uprooting forces…feeder roots extending laterally.

Tropical soils are nutrient poor.

Roots must traverse the surface for minerals, so roots grow on the surface (not tap root).

So, to keep this tall baobab tree standing upright, the roots grow in diameter but only in the vertical dimensions to form ridge roots…called buttress roots.

My wife here is as large as I am so you can see these roots are a meter tall!

These roots inspired gothic cathedral architects to design buttress walls.

http://www.dublincity.ie/dublin/citywalls/buttress.jpg

http://www.oxc.com.hk/raoul_nathalie/gallery/images/04%20Buttress.jpg

Pandanus utilis - screw pineProp roots such as these inspired flying buttresses.

http://www.contrib.andrew.cmu.edu/~ajm/Pages/Graphics/flyingbuttress.JPG

http://williamcalvin.com/BHM/img/FlyingButtressND.jpg

•Stems-support the leaves, flowers, and fruit.

Woody Stems

•Are tough and winter hardy. They often have bark around them.

Herbaceous Stems•Succulent, often green, and will not survive winter in cold climates

Modified Stems-bulbs, corms, rhizomes,

tubers

•Not all stems are erect, above ground structure. Some grow along the ground or even underground. Some stems have specialized jobs to perform.

Bulbs•Short stems that are

surrounded by modified leaves called scales.

•Examples: Easter lilies and onions

Corms•Thickened, compact, fleshy stems

•Example: Gladiola

Rhizomes•Thick stems that

run below the ground

•Examples: Johnson grass and the iris

Tubers•Thickened

underground stems that store carbohydrates

•Example: The Irish potato

•The internode is the area between the nodes

•The axillary bud grows out of the axil

Draw this to turn in

•The lenticels are pores in the stem that allow the passage of gases in and out of the plant

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Radish seedlings have roots with long root hairs that increase the surface area for water and mineral uptake