Kingdom Plantae

The Body’s Organization

Each level represents a different compartment Organism Organs Tissues Cells Organelles

Multicellular Organisms 700-500 mya Eukaryotic Cells 1.7 bya

Major Evolutionary Events in the Origin of Life

First Cells Prokaryotes “the animation of matter” 3.5 bya Primordial Soup

Domains:

Eubacteria

Kingdoms:

Archaea Archaebacteria Eukarya Animal Fungi Plant Protist Eubacteria Common ancestor

Introduction to Plants

• Based on weight, plants are the

dominant

group of organisms on land. This is called biomass.

• Most plants are

photosynthetic

.

– They produce

organic

materials from

inorganic

materials by

photosynthesis

.

• A few plant species live as

parasites

.

– Many parasitic plants cannot photosynthesize.

•

Importance of Plants

Asthetics • Medicine • Food • Industrial products • Recreation • Air quality • Water quality • Climate • Fish and wildlife habitats • Ecosystem

Introduction to Plants

• • Plants probably

evolved

from multicellular aquatic green algae that could not survive on land. Through mutations and natural selection, plants changed enough and some survived. (Evolutionary viewpoint)

Multicellularity

enabled plants to develop features that helped them live more successfully on land.

Introduction to Plants

Before plants could thrive on land, they had to be able to: – Absorb nutrients from their surroundings.

– Prevent their bodies from drying out.

– Reproduce without water to transmit sperm.

Absorbing Nutrients

• • On land, most plants take nutrients from the soil with their

roots

.

Fungi

have helped land plants to get nutrients from Earth’s rocky surface.

–

Symbiotic

relationships referred to as mutualism between fungi and the roots of plants are called

mycorrhizae

.

– Today, about 80% of all plant species form mycorrhizae.

Preventing Water Loss

• The first plants lived at the edges of bodies of water, where drying out was not a problem.

• A

watertight

covering, which reduces water loss, made it possible for plants to live in drier habitats.

– This covering, called the

cuticle

, is a waxy layer that covers the non-woody aboveground parts of most plants.

Preventing Water Loss

• • The

cuticle

does not let oxygen or carbon dioxide pass through it.

• Pores called

stomata

permit plants to exchange oxygen and carbon dioxide.

–

Stomata

extend through the

cuticle

outer layer of cells (epidermis).

and the • A pair of

guard cells

border each stoma.

Stomata

open and close as the guard cells change shape.

Preventing Water Loss

Reproducing on Land

• Aquatic algae reproduce sexually when

sperm

swim through the water and fertilize eggs.

• The

sperm

of most plants must be able to move without water.

• • In most plants,

sperm

are enclosed in a structure (

pollen

) that keeps them from drying out.

Pollen

permits the sperm of most plants to be carried by wind or animals rather than water.

Four Types of Plant Tissue

A growing plant is like building a house!

•

Building a House

1. Foundation is laid 2. Construction of the frame 3. Installation of plumbing, heating, etc 4. Waterproof walls and roof 5. Food stored in appropriate places •

Building a plant

1. Meristems give rise to all tissues 2. Three tissue systems give rise to the major organs of a plant 3. Installation of the vascular tissue (plumbing) 4. Installation of dermal tissues – covering, skin 5. Installation of ground tissue – parenchyma

Meristematic Tissue

• Meristems are regions of cell division • Main difference between animals and plants • Birds and mammals stop growing at maturity, although certain cells get replenished (skin) • Plants have the ability to keep growing their entire lives • Meristems make it possible to grow a new plant from a cutting • Growth in plants is the counterpart (to some extent) to movement in animals

Epidermis –

stoma, trichomes, & root hairs http://www.ucd.ie/botany/Steer/hair/roothairs.html

Cell Division: Mitosis (nuclear division) + Cytokinesis (cytoplasmic division) 1. Interphase 2. Prophase 3. Metaphase 4. Anaphase 5. Telophase 6. Cytokinesis Illustration from: http://biology.nebrwesleyan.edu/benham/mitosis/

Vascular Tissue, Seeds and Flowers

• One of the most important structures in plants is the conducting tissues that move water and other materials through the plant body.

• Without these structures, plants would remain very small.

Advantages of Conducting Tissue

• Some plants are small.

– Materials are transported within their bodies by

osmosis

and

diffusion

.

• Specialized cells that transport water and other materials within a plant are found in

vascular tissues

.

• The existence of vascular tissue allows for larger and more complex plants.

Advantages of Conducting Tissue

• The larger, more complex plants have a

vascular system

.

– A system of well-developed vascular tissue that distributes materials more efficiently.

• Three groups of plants alive today lack a vascular system.

– These plants are called

nonvascular plants

.

• Plants that have a vascular system are called

vascular plants

.

Advantages of Seeds

• A

seed

is a structure that contains the embryo of a plant.

– An

embryo

is an early stage in the development of plants and animals.

• Most plants living today are

seed plants

.

– Vascular plants that produce seeds.

Advantages of Seeds

• •

Protection

– Seeds are surrounded by a protective cover called the seed coat.

– The seed coat protects the embryo from drying out and from mechanical injury and disease.

Nourishment

– Most kinds of seeds have a supply of nutrients stored in them.

– These nutrients are a ready source of nourishment for a plant embryo as it starts to grow.

Advantages of Seeds

•

Plant Dispersal

– Seeds disperse (spread) the offspring of seed plants.

– Many seeds have structures that help wind, water, or animals carry them away from their parent plant.

– Dispersal prevents competition for water, nutrients, light, and living space between parents and offspring.

Advantages of Seeds

•

Delayed Growth

– The embryo in a seed is in a state of suspended animation.

– Most seeds will not sprout until conditions are favorable. • Such as when moisture is present and the weather is warm.

– Seeds make it possible for plant embryos to survive through unfavorable periods such as droughts or cold winters.

Advantages of Flowers

• The flower is a reproductive structure that produces pollen and seeds.

• Most plants living today are flowering plants – seed plants that produce flowers.

– The pollen of the first seed plants are believed by evolutionists to be carried by wind.

– Large amounts of pollen are needed to ensure cross-pollination by wind – an inefficient system.

Advantages of Flowers

• Many flowers attract animals, such as insects, bats, and birds.

• Tiny pollen grains stick to animals, which carry pollen directly from one flower to another.

• Flowering plants that are pollinated by animals produce less pollen, and cross-pollination can occur between individuals that live far apart.

Plant Life Cycles

• Plants have life cycles in which haploid plants that make

gametes

(

gametophytes

) alternate with diploid plants that make

spores

(

sporophytes

).

– A life cycle in which a gametophyte alternates with a sporophyte is called

alternation of generations

.

Alternation of Generations

Vascular-Plant Sporophyte

•

Vascular System

– Larger bodies require an efficient vascular system for transporting materials internally.

– The sporophytes of vascular plants have two types of

vascular tissue

.

– Each type of vascular tissue contains strands of long, tube like cells that are lined up end to end like sections of pipe.

– These strands of cells transport water and nutrients within a plant’s body.

Vascular-Plant Sporophyte

– Soft-walled cells transport organic nutrients in a tissue called

phloem

.

– Hard-walled cells transport water and mineral nutrients in a tissue called

xylem

.

• The walls of the water-conducting cells in xylem are thickened, which helps support the plant body.

– This makes it possible for vascular plants to grow to great heights.

Vascular-Plant Sporophyte

Vascular-Plant Sporophyte

•

Distinctive Body Form

– Nearly all plants have a body that consists of a vertical shaft from which specialized structures branch.

– The part of a plant’s body that grows mostly upward is called the

shoot

.

– In most plants, the part of the body that grows downward is called the

root

.

Vascular-Plant Sporophyte

– Zones of actively dividing plant cells, called

meristems

, produce plant growth.

– The vertical form of the plant body results as new cells are made at the tips of the plant body.

Kinds of Plants

•Nonvascular •Vascular without Seeds •Vascular with Seeds

Kinds of Plants

•Nonvascular •Vascular without Seeds •Vascular with Seeds

Nonvascular Plants

• Nonvascular plants do not have a vascular system for transporting water and other nutrients within their bodies.

• All nonvascular plants lack true roots, stems, and leaves.

– Although most have structures that resemble them.

Features of Nonvascular Plants

•

Require Water for Sexual Reproduction

– Nonvascular plants must be covered by a film of water in order for fertilization to occur.

– Eggs and sperm form in separate structures, which are often on separate plants.

– The gametophytes grow in mats tightly covered by a film of water; sperm can easily swim to neighboring individuals and fertilize their eggs.

Classification of Nonvascular Plants

• Bryophytes Small with leaflike, stemlike, and rootlike structures. Mosses usually only grow to 1 inch. Disseminated by spores: mosses, liverworts, hornworts Mosses Bryophyta Liverwort Hepatophyta Hornwort Anthocerophyta

Bryophyte Reproduction

Mosses and Medicine

• Moss has been used as an

antiseptic

centuries.

for • In World War I, moss was used to treat soldier’s wounds in emergency situations.

• The antiseptic qualities result from moss’ natural absorbency and acidity.

Mistaken for Mosses

• A variety of plants and plantlike organisms are mistakenly called mosses.

– Irish moss is a red alga.

– Spanish moss is a flowering vascular plant.

– Reindeer moss is a lichen.

Kinds of Plants

•Nonvascular •Vascular without Seeds •Vascular with Seeds

Seedless Vascular Plants

Features of Seedless Vascular Plants

•

Vascular System

– Have both

xylem

and

phloem

.

– The water-conducting cells in the

xylem

are reinforced with

lignin

, a major part of wood.

– Lignin bonds with cellulose to make a sturdy, strong cell walls.

– Because of their vascular system, they grow much larger than nonvascular plants and also develop true roots, stems, and leaves .

•

Classification of Seedless Vascular Plants

Ferns

– Phylum

Pterophyta

are the most common and most familiar seedless vascular plants.

– Ferns grow throughout the world, but they are most abundant in the tropics.

– The plants that are recognized as ferns are sporophytes.

Reproduction of Seedless Vascular Plants

– Most fern sporophytes have rhizomes that are anchored by roots and leaves called

fronds

.

• The coiled young leaves of a fern are called

fiddleheads

.

– Spores are produced in

sporangia

that grow in clumps called

sori

on the lower side of fronds.

Sori

– The

gametophytes

of ferns are flatted, heart shaped green plants that are usually less than 1 cm across.

Kinds of Plants

•Nonvascular •Vascular without Seeds •Vascular with Seeds



Gymnosperms



Angiosperms

Gymnosperms

• Seed plants whose seeds do

not

develop within a sealed container (a fruit).

• The word comes from the Greek words

gymnos

, meaning “

naked

,” and

sperma

, meaning “

seed

.”

Features of Gymnosperms

•

Seeds

– All gymnosperms produce seeds.

– Seeds

protect

plant embryos, provide them with

nutrients

, and permit them to

survive

long periods of unfavorable conditions.

– In some plants, seeds also disperse new plants far from their parents.

Features of Gymnosperms

•

Greatly Reduced Gametophytes

– All seed plants produce very tiny

gametophytes

two types.

• Male and female.

– The

gametophytes

form within the tissues of the

sporophytes

.

of – Grains of pollen are male gametophytes.

– Female gametophytes form within structures that become seeds.

– In all but one species of gymnosperm, male and female gametophytes develop in male and female cones.

Features of Gymnosperms

•

Wind Pollination

– The

sperm

of gymnosperms do not swim through water to reach and fertilize eggs.

– Instead, the sperm are carried to the structures that contain eggs by

pollen

, which can drift on the

wind

.

–

Wind

pollination makes sexual reproduction possible even when conditions are very dry.

Kinds of Gymnosperms

•

Conifers

– Phylum

Coniferophyta

are the most familiar and most successful gymnosperms.

– Conifers have

leaves

reduced to tiny scales.

• These leaves are an

adaption

for limiting water loss.

that are either needle-like or

Kinds of Gymnosperms

– Some of the tallest living plants, the redwoods of coastal California and Oregon are conifers.

– The oldest trees in the world are thought to be bristlecone pines, a species of conifer that grows in the Rocky Mountains and Great Basin.

• Some bristlecone pines are about 5,000 years old.

– Vast forests of conifers grow in cool, dry regions of the world.

Kinds of Gymnosperms

•

Cycads

– Phylum

Cycadophyta

palm-like leaves.

have short stems and – Cones that produce pollen and those that produce seeds develop on different plants.

– Cycads are widespread throughout the tropics.

Kinds of Plants

•Nonvascular •Vascular without Seeds •Vascular with Seeds



Gymnosperms



Angiosperms

Angiosperms

• Most seed plants are flowering plants or angiosperms.

• Angiosperms produce

seeds

that develop enclosed within a specialized structure called a

fruit

.

• The word comes from the Greek words

angeion

, meaning “

case

,” and

sperma

, meaning “

seed

.”

Features of Angiosperms

•

Flowers

– The male and female gametophytes of angiosperms develop within flowers which promote

pollination

and

fertilization

more efficiently than do cones.

– Some flowers, such as roses, are brightly colored or have strong scents.

• This

attracts

insects and other animals that carry pollen and increases the likelihood of crosspollination, which often occurs before the flowers open.

Features of Angiosperms

•

Fruits

– Although fruits provide some protection for developing seeds, their primary function is to promote seed dispersal.

– The angiosperms produce many different types of fruits, which develop from parts of flowers.

– Many fruits are eaten by animals and pass undigested from the animals’ bodies.

– Other fruits have structures that help them float on wind or water.

– Some fruits even forcefully eject their seeds, flinging them away from the parent plant.

Kinds of Angiosperms

•

Botanists

divide the angiosperms into two subgroups,

monocots

and

dicots

.

• The

monocots

are flowering plants that produce seeds with one seed leaf (

cotyledon

).

– Most monocots also produce flowers with parts that are in multiples of three and have long, narrow leaves with parallel veins.

Kinds of Angiosperms

• The

dicots

are flowering plants that produce seeds with two seed leaves, dicotyledons.

– Most dicots also produce flowers with parts in multiples of two, four, or five and have leaves with branching veins.

Familiar Families of Angiosperms

Subgroup Family Examples Monocots

Iridaceae (Iris) Irises, gladiolus, crocus

(class Monocotyledonae) Dicots (class Dicotyledonae)

Liliaceae (Lily) Poaceae (Grass) Asteraceae (Aster) Brassicaceae (Mustard) Fabaceae (Legume) Rosaceae (Rose) Solanaceae (Nightshade) Daylilies, tulips, asparagus, aloe vera Wheat, corn, rice, lawn grasses Daisies, sunflowers, lettuce, ragweed Broccoli, cauliflower, turnips, cabbage Beans, clovers, peas, peanuts, soybeans Roses, apples, peaches, pears, plums Potatoes, tomatoes, peppers, petunias

Plants as Food

• Humans depend on plants in many ways.

• Plants store the extra nutrients they make or absorb in their bodies.

• Plant parts contain organic nutrients (carbohydrates, fats, and proteins) and minerals (calcium, magnesium, and iron).

• All types of plant parts – roots, stems, leaves, flowers, fruits, and seeds – are eaten as food.

Fruits and Vegetables

• To a

botanist

that contains , a

fruit

is the part of a plant

seeds

.

• A

vegetative

part is any nonreproductive part of a plant.

• The foods that you think of as

fruits

(such as apples, bananas, and melons) are also fruits in the botanical sense.

• Vegetables that contain seeds are fruits in the botanical sense such as cucumbers or tomatoes.

• Fruits and vegetables provide

dietary fiber

and are important sources of essential

vitamins

and

minerals

.

•

Root Crops

Potatoes

are an important food staple in many parts of the world.

– Rich in calories and easy to grow, potatoes are an ideal crop for a small farm.

– They are classified as root crops because they grow underground.

– Potatoes are actually

tubers

, modified underground stems that store starch.

• Yams, an essential food crop in many tropical parts of the world, are roots.

• Sweet Potatoes, carrots, radishes, turnips, beets, and cassava are important root crops.

– These vegetables are enlarged roots that store starch.

Legumes

• Many members of the pea family, which are called

legumes

, produce protein-rich seeds in long pods.

– About 45% of a

soybean

grown for food, is protein.

, the most important legume • Soybeans are often cooked and pressed into cakes called

tofu

.

• • Peas, peanuts, and the many different types of beans are the

seeds

of legumes.

Alfalfa

, which is fed to livestock, is another important legume.

– Like many legumes, alfalfa has its roots.

nitrogen-fixing

bacteria, which add nitrogen compounds to the soil, in • Alfalfa is also grown to enrich the soil.

• Student handout ends at this point; however, the following slides will be presented during a plant lab.

Cereals

•

Cereals

are

grasses

that are grown as food for humans and livestock.

• Cereal grasses produce large numbers of type of edible, dry fruit called a

grain

.

• A

grain

contains a single seed with a large supply of

endosperm

.

• Each grain develops from a

flower

.

• The flowers of cereal grasses form in tightly packed clusters of many individual flowers.

Cereals

• A grain is covered by a dry, papery husk called the

ovary

fiber.

and the • More than

70% bran seed coat

• Cereal grains are rich in growing cereal grains.

wheat, corn, and rice.

.

that humans consume come , which includes the wall of the carbohydrates and also contain protein, vitamins, and dietary of the world’s cultivated farmland is used for • More than half of the calories from just three cereal grasses:

Wheat

• For more than 1/3 of the world’s population, wheat is the primary source of food.

• The

endosperm

of wheat grains, which is high in

carbohydrates

, is commonly ground into white flour and used to make breads and pasta.

• Vitamin-rich wheat germ consists of the

embryos

of wheat grains.

• Whole-wheat flour consists of the

endosperm

plus the

germ

and

bran

layers.

Wheat

• Wheat grains are not always ground into flour.

– In the Middle East, wheat grains are often boiled or soaked, dried and then pounded until they crack.

• Most wheat is grown in temperate regions that have fertile soil and moderate rainfall.

– One of the world’s best wheat-growing areas is the Great Plains region of the US and Canada.

Corn

• Corn is the most widely cultivated crop in the US.

• American colonists of the 1600s and 1700s first learned how to grow corn from Native Americans.

• In the southeastern US, corn was more widely grown than wheat, which does not grow as well in hot climates.

• Foods that are made from corn include corn bread, corn pone, hominy, and grits.

Corn

• About 70% of the corn crop harvested in the US is consumed by livestock.

• Other uses for corn include the production of corn syrup, margarine, corn oil, cornstarch, and fuel-grade ethanol.

• Most of the corn grown in the US today comes from a region known as the Corn Belt, which includes Iowa, Nebraska, Minnesota, Illinois, and Indiana.

Rice

• For more than half of the people in the world, rice is the main part of every meal.

• Although it is low in protein, rice is an excellent source of energy rich

carbohydrates

.

• While brown rice still has its vitamin-rich bran layers, white rice has been processed to remove the bran layers.

– This processing helps to prevent spoilage in stored rice.

– In societies where people eat mainly rice, vitamin-rich sauces such as soy sauce are often added to white rice to make meals more nutritious.

Rice

• The white rice you buy at a grocery store is enriched with added vitamins.

• Rice is often added to processed foods such as breakfast cereal, soup, baby food, and flour.

• In the US, rice is grown in central California, in the Southeast, and along the Gulf Coast in fields.

Nonfood Uses of Plants

•

Wood

– After food, wood is the single most valuable resource obtained from plants.

• Many products such as furniture, buildings, boats, cabinets, and violins are made from wood.

– The wood from trees that have been cut down and sawed into boards, is called

lumber

.

• Nearly 75% of the lumber cut in the US is used for building construction.

• The rest is used to make products that contain wood, or it is ground and moistened to make

wood pulp

.

• Wood pulp is made into paper, rayon, and many other products.

– For more than a quarter of the world’s people, wood is still the main source of fuel for

heating

and

cooking

.

Nonfood Uses of Plants

•

Medicines

– By studying the plants traditionally used to treat human ailments, researchers have developed many “modern” medicines.

Name Caffeine Codeine Cortisone Digitalis Ephedrine Salix Taxol Source

Tea leaves Poppy fruits Yam tubers Foxglove leaves Ephedra stems

Action

Acts as a stimulant Relieves pain Relieves symptoms of allergies Stabilizes irregular heartbeats and treats cardiac disorders Acts as a decongestant Bark of willow trees Relieves aches and pains (aspirin) Yew tree bark Reduces the size of cancerous tumors

Nonfood Uses of Plants

•

Fibers

– Fibers are strands of

cellulose

, which is a component of the cell walls of plants.

– In plants, fibers help provide support for plant body.

– The strength and flexibility of plant fibers make them ideal materials for making paper, cloth, and rope.

• Most of the fibers used to make paper come from wood.

– Paper-making fibers are also obtained from many other plants, including cotton, flax, rice, bamboo, and papyrus.

Nonfood Uses of Plants

– For centuries, people have made clothing with cloth made of

cotton

, the world’s most important plant fiber.

• White fibers fill up the inside of a cotton boll, the fruit of the cotton plant.

• Cotton thread is spun from the fine white fibers, which grow on cotton seeds.

– The stems of

flax

yield softer, more durable fibers that are used to make linen.

– More than 30% of the world’s clothing is now made of synthetic fibers, but natural plant fibers are still prized for their durability and comfort.

– Sturdy fibers of

hemp

and

sisal

plants are used to make rope.