Plant Diversity

The Classification of Plants

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 (xylem & phloem)

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 -NONVASCULAR

1. Most primitive plants

2. Found in moist, shady areas b/c no true roots

3. NO vascular (transport) system

4. Reproduces using spores

5. 5. 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. 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

• 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

Angiosperms- “enclosed seeds”

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

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

3. 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

Flower Anatomy

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

http://vimeo.com/1594037?pg=embed&sec=1594037

Fill in Your Flower!

stigma

style

ovaryovule

carpelanther

filamentstamen

petal

sepal

receptaclepeduncle

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Pollination is the transfer of pollen from the anther to the stigma

• This is an example of cross-pollination as the pollen travels from one flower to a different flower. This is desirable in plants as it promotes variation.

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Self-pollination occurs when pollen falls from the anther onto the stigma of the same flower

• Self-pollination is not desirable as it reduces variation

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Flowers will prevent self-pollination by either having stigma above stamen or…

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

…by having stamen and stigma mature at different times.

Flower Structure Pollination Fertilisation Seed Dispersal Germination Test

Once pollination occurs a tube grows from the pollen grain down through the style to the ovule

Flower Structure Pollination Fruit Development Seed Dispersal Germination Test

stigma

style

ovary

ovule

carpel Note: Petals not shown in order to simplify diagram

Fertilisation occurs when the male gamete fuses with the ovule (the female gamete)

Flower Structure Pollination Fruit Development Seed Dispersal Germination Test

Angiosperms can be categorized as monocots and dicots.

Angiosperms

Monocots Dicots

After fertilisation the petals, stamen and sepals fall off.The ovule turns into a seed, the fertilised egg inside develops into an embryo plant.

Testa: tough seed coat

Micropyle:Hole made by pollen tube

Embryo plant

Cotyledon:Food store

Plumule:Embryo shoot

Radicle:Embryo root

Flower Structure Pollination Fruit Development Seed Dispersal Germination Test

Water leaves the seed, it dehydrates and becomes dormant because metabolic reactions stop.The ovary develops to become a fruit.

seedFleshy wall of the ovary(yes, you are eating an adapted ovary when youcrunch into an apple!

Flower Structure Pollination Fruit Development Seed Dispersal Germination Test

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?