Plant Diversity

The Evolution and Classification of

Plants

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PLANT CHARACTERISTICS

• Multicellular eukaryotes

• Photosynthetic autotrophs containing chloroplasts.

• Non-mobile (fixed to one spot)

• Cell walls made of cellulose

• Responds to environment and grows through the use of hormones

Slide # 3

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 out

4. How to reproduce without water

Plants Make the The Move to LandSlide # 4

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

Some Adaptations (solutions)-

1. Have body parts extending into both air and soil

2. Develop a vascular system to transport resources in plant

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

4. Specialized structures for reproduction including spores & seeds that do not dry out

Slide # 5

Plants are classified based on whether or not they have

1. Vascular System (transport)

2. Seeds

3. Flowers (enclosed seeds)

Slide # 6

Concept Map: Plants are divided 1st by whether or not they have a vascular system.

Bryophytes Tracheophytes

Plants

Has Vascular Tissue

Has NO Vascular Tissue

Slide # 7

Bryophytes -NONVASCULAR1. Most primitive plants

2. Found in moist, shady areas

3. NO vascular (transport) system

4. Small size due to no vascular tissue

5. No true roots, stems, or leaves

6. Needs water for reproduction.

7. Reproduces using spores, -a water-proof single cell that can grow into a new organism.

8. Most common example: Mosses

Slide # 8

Typical Moss Plant (most common bryophyte)

Spores form inside the capsule.

Notice the problem of nutrient separation into air and soil is solved with underground and

above ground parts. (Although NO TRUE roots,

stems or leaves are present)

Slide # 9

Tracheophytes-Vascular Plants-

1. Contains two types of specialized vascular tissues for transport within the plant:

a. Xylem- transports H20 up from roots.b. Phloem- transports food made during

photosynthesis and nutrients to where they are needed in the plant.

2. Presence of a vascular system allowed plants to become tall.

3. Has specialized organs: roots, stems, and leaves.

Slide # 10

Tracheophytes are divided into two groups by whether or not they reproduce with seeds.

Tracheophytes

Seedless Seeded

Ferns use spores

Slide # 11

1. Contain a vascular system.

2. They grow in moist, shady habitats.

3. Has underground stems, roots, & large leaves called fronds.

4. Reproduce using spores, Not seeds.

The Fern - a seedless vascular plant

There are

11,000 species of ferns.

Sori

Slide # 12

ADVANTAGE: Developed reproductive strategies that do not need water:

1. Seed contains a. A fully developed embryo

b. Food supply for embryo

c. A water-proof seed coat to keep from drying out

2. Sperm transferred in water-proof pollen through pollination by wind or animals.

3. Developed seed-bearing structures: Cones and Flowers

Seed-Bearing TracheophytesSlide # 13

The two Seeded Tracheophyte groups are divided by whether or not they have enclosed seeds -protected inside a fruit or if seeds are

exposed to the environment.

Tracheophytes

Seedless Seeded

Ferns use spores

Gymnosperms Angiosperms

“naked” or exposed seeds Flowers produce fruit

w/ enclosed seeds

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

junipers, yews, & cypress trees)

Gymnosperms- “naked seed”

Sago Palm Ginkgo Ginkgo

Slide # 15

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-ConifersSequoia

JuniperPine

Slide # 16

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

Slide # 17

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.

Slide # 18

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

1. Winged fruit – glides to new location (maple fruit)

2. Floating fruit – can float to new locations (coconut)

3. Fleshy fruit - sweet bright colored fruit have seeds that survive the digestive system of animals that eat the fruit (apple)

4. Spiny fruit- Velcro like projections attach to the fur of animals (cockleburs)

Slide # 19

Maple seeds: Winged fruit

Burdock: Spiny fruit