Plant DiversityThe Evolution and Classification of

Plants

Why should we care about plants, at all?

Carbon dioxide levels

Indicators for ground level pollution, long before animals

Japan/ radioactive food….

But…

Kudzu- invasive

Did you know……

Oak trees do not reach sexual maturity with acorns until they are fifty years old or older

And that you are 16 times more likely to be struck by lightning if you’re standing under an oak tree than any other type of tree

Did you know….

Bamboo can grow up to three feet in a 24 hour period.

Did you know…

The squirting cucumber (Ecballium elaterium), when brushed by a passerby, ejects its seeds and a stream of poisonous juice that stings the skin

Did you know…

Fruits have become more expensive because we have killed more bees (and birds) with insecticides….

What do I know about plants?True or False

1. All plants perform photosynthesis.2. All plants need water and

nutrients.3. All plants reproduce using flowers.4. All plants reproduce using seeds.

5. Plants eat soil6. Some plants lose their leaves in the

winter because it gets too cold7. Plants know their up from their down8. Plants have hormones the same way

we do9. Leaves are different on the two sides

Random thought questions….

• Are there girl and boy plants?• Why are mosses so short, and why

do they live only in moist areas?• When you eat an apple, what are

you really eating?• If this whole ‘we came from

bacteria thing’ is true, where do scientists think plants came from?

Precursors to plants…algae?

PLANT CHARACTERISTICS:• Multicellular,eukaryotic, autotrophic• Can’t move• Photosynthesize and have chlorophyll • Cell Walls made of cellulose

The ancestors of plants were multicellular green algae. They were completely immersed in water & dissolved

minerals.

1. How to get chemical resources (water, minerals, oxygen, and carbon dioxide) separated into air and soil

2. How to transport resources within the plant.3. How to prevent from drying out4. How to reproduce without water

Plants Make the Move to Land

To move onto land, plants had to solve these problems:

1. Have a protective layer – cuticle (waxy outer layer) to keep from drying out

Some Adaptations (solutions)-

2. Have body parts extending into both air and soil (roots)

3. Have leaves – photosynthesis takes place on tops of leaves

Some Adaptations (solutions)-

4. Develop a vascular system to transport resources in plant

5. . Specialized structures for reproduction including spores & sex cells (seeds) that do not dry out

Some Adaptations (solutions)-

Plant Growth: In response to seasons …

Evergreen Deciduous

Plant Growth: In response to stimuli …

Gravitropism Phototropism

They grow towards light, which is usually away from where gravity is trying to pull them …

Plants are classified based on whether or not they have

1. Vascular System ( pipes for transport)

2. Seeds 3. Flowers (enclosed seeds)

Nonvascular Plants

1. Most primitive plants2. NO “pipes” (vascular system)3. Small size due to no vascular tissue 4. No true roots, stems, or leaves5. Most common example: Mosses,

liverworts

Nonvascular Plants6. Need WATER to

reproduce7. Reproduction can be

sexual or asexual8. Tend to be located

near water or in moist/shady places.

Typical Moss Plant (most common bryophyte)

NO TRUE roots, stems

Tracheophytes (Ferns)-Vascular Plants-

Contains vascular tissues.. But not much else!

1. Contain a vascular system – can grow taller than mosses

2. They grow in moist, shady habitats.- WHY?????

The Fern - a seedless vascular plant

There are 11,000 species

of ferns.

Vascular-seedless3. Has underground

stems, roots, & large leaves called fronds.

4. Reproduction can be sexual or asexual

5. Example: Ferns, horsetails, club mosses

• Cycad (Sago palm), • Ginkgo, • Conifer (pine, spruce, firs, cedars,

sequoias, redwoods, junipers, yews, & cypress trees)

Gymnosperms- “naked seed”

Sago Palm Ginkgo Ginkgo

Gymnosperms• Have pipes and seeds, but no

flowers• Reproduction relies on wind and

water• Use cones and pollen• Example: Pine trees

1. Most common gymnosperms are Conifers

2. Conifers have leaves called needles or scales have a reduced surface area and thick waxy coat on the needle to reduce water loss and prevents freezing.

Gymnosperms-Conifers

Sequoia

JuniperPine

How do gymnosperms spread their seeds?

Conifer Reproduction

1. Male cones produce pollen and the female cone produces eggs and seeds.

2. Pollen is inefficiently transferred by the wind.

3. Once mature, the scales on the female cone dry out and open scattering the seeds by the wind.

Pollen

Pollen Cone

Seed Cone

Angiosperms- “enclosed seeds”

Angiosperms- “enclosed seeds”

1. These are flowering plants the encourage direct and efficient pollen transfer (smell, color and offering nectar)

2. Pollinators are flying insects, birds, and bats that transfer pollen from flower to flower.

3. Flowers contain ovaries, which is where eggs/seeds are produced.

4. A fruit is the pollinated ovary containing mature seeds.

Angiosperms- “enclosed seeds”• Has pipes, seeds, and flowers• Reproduction with flowers: • Male Parts: stamen (anther and

filament)• Female Parts: Pistil (stigma, style,

overy)

Fruit can aid in dispersal of seed to reduce competition with parent plant.

1. Winged fruit2. Floating fruit3. Fleshy fruit4. Spiny fruit

Maple seeds: Winged fruit

Burdock: Spiny fruit

Review of Plant Evolution:

Quiz Time• What did plants have to overcome to live on

land?• What is the most primitive division of plants

because they have no vascular system?• What is the most common example in this

division and how do they reproduce?• Why are mosses so small?• What is the division of plants that contain a

vascular system?• What did a vascular system do for plants size-

wise?• How are mosses and ferns different?• How are mosses and ferns alike?

Quiz Time• How are Tracheophytes different from

bryophytes?• How are tracheophytes divided?• What are the advantages of seeds over

spores?• What other advantages did seed-bearing

plants have over spore-bearing plants?• What are the two divisions of the seed-

bearing tracheophytes?

Quiz Time• What does the term Gymnosperm mean?• What are the most common of the

Gymnosperms?• What is the evolutionary importance of

needles? • What structures do conifers use to reproduce?• Were are seeds located in the cone?• Even though wind-dispersal of pollen is

inefficient, what did it allow plants to overcome?