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Plant Diversity II: Seed Plants

Angiosperms and Gymnosperms

Pesticides!

Include:

Herbicides

Insecticides

Fungicides

Rodenticides

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Pesticides are pervasive Studies of major rivers and streams document

that 96% of all fish,

100% of all surface water samples

33% of major aquifers contain one or more pesticides at detectable levels

Surface water= In a large sampling of streams throughout the country, USGS found 46 pesticides and pesticide degradation products in one or more samples

Groundwater= A 1989 study found residues of 39 pesticides and their degradation products in the groundwater of 34 states and Canadian provinces

Dozens of pesticides and their degradation products contaminate waterways and escape regulatory oversight

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Runoff from urban lawn pesticides contaminates local watersheds and stresses municipal water treatment.

Pesticides harm humans Human health effects,

including low birth weights,

breast cancer, and

low sperm counts are linked to herbicide-contaminated water

Children are not adequately protected by federal limits of pesticides in water.

USGS found that more that 90% of water and fish samples from all streams sampled in the U.S. contain at least one pesticide

USGS. 1999. The Quality of Our Nations Water: Nutrients and Pesticides. USGS Circular

1225. [http://permanent.access.gpo.gov/waterusgsgov/water.usgs.gov/pubs/circ/circ1225/]

Kettles, MA, SR, Browning, TS Prince, and SW Horstman.

1997. Triazine herbicide exposure and breast cancer

incidence: An ecologic study of Kentucky counties.

Environmental Health Perspectives 105(11):1222-1227.

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Pesticides harm wildlife

Frogs exhibit hermaphrodism when exposed to legally allowable levels of the herbicide atrazine in waterways

A study of sex hormones in carp indicates that pesticides may be affecting the ratio of estrogen to testosterone in both male and female fish.

They have also caused fish kills.

Goodbred, S.L., Gilliom, R.J., Gross, T.S., Denslow, N.P., Bryant, W.L., and Schoeb, T.R., 1997, Reconnaissance of 17b-estradiol, 11-

ketotestosterone, vitellogenin, and gonad histopathology in common carp of United States streams—potential for contaminant-induced

endocrine disruption. U.S. Geological Survey Open-File Report 96-627.

1. Which of the following is NOT a plant adaptation for life on land?

a) Roots, which stabilize and absorb water and nutrients from soil

b) A waxy cuticle, which prevents water loss

c) Colonial living, which maximizes use of resources while expending less energy

d) Stomata, which allow for gas exchange

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1. Which of the following is NOT a plant adaptation for life on land?

A. Roots, which stabilize and absorb water and nutrients from soil

B. A waxy cuticle, which prevents water loss

C. Colonial living, which maximizes use of resources while expending less energy

D. Stomata, which allow for gas exchange

2. Why is water needed for bryophyte reproduction?

A. Both the sperm and the egg develop in spores, which must swim through water to undergo fertilization.

B. The sperm must swim to the egg.

C. Without water, the sperm will fertilize the egg, but the embryo will not develop.

D. Without water, the embryo will remain haploid instead of diploid.

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2. Why is water needed for bryophyte reproduction?

A. Both the sperm and the egg develop in spores, which must swim through water to undergo fertilization.

B. The sperm must swim to the egg.

C. Without water, the sperm will fertilize the egg, but the embryo will not develop.

D. Without water, the embryo will remain haploid instead of diploid.

3. What is one of the main differences between club moss and moss?

A. Club moss has vascular tissue.

B. Moss has leaves; club moss does not.

C. To conduct water and nutrients, club moss has rhizoids rather than vessels.

D. Moss has sperm and egg within the same spore; club moss has them in different spores.

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3. What is one of the main differences between club moss and moss?

A. Club moss has vascular tissue.

B. Moss has leaves; club moss does not.

C. To conduct water and nutrients, club moss has rhizoids rather than vessels.

D. Moss has sperm and egg within the same spore; club moss has them in different spores.

What’s special about seeds?

Seeds allow the embryo to go dormant for a long period of hard conditions: cold or dry winters

Allows a wider range of dispersion

Seed coat

Endosperm

=Stored food

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Alternating Generations In more advanced plants, the sporophyte generation is dominant.

Alternation of generations modified

Pollen= Male gametophyte Contains sperm

Ovule= Female gametophyte Contains egg

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How is pollen an adaptation?

Allows fertilization to occur even in the absence of available water.

Moss fertilization

Pollen grains

water

Gymnosperms:“naked seed”

Coniferophyta (pines and cone bearing trees)

Cycads (palmlike)

Ginkgos (ginkgo trees)

Gnetophyta (gnetums)

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Gymnosperms: Ginkgo Long thought to be extinct in western civilization, until travelers from Germany found it while visiting temples in China and Japan.

Fleshy outer covering to seed–looks like a fruit

Cycads

Palm-like plants, but have cones for reproduction

Tropical

Endangered by poaching and a black market

Gymnosperms: Cycadophyta

23% of 305 extant

species endangered,

15% vulnerable

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Ephedra Welwitchsia Gnetum

• Flower-like structures

Temperate regions

except Australia Namibia Old and New

World Tropics

Gymnosperms: Gnetophyta

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Gnetophyta: Welwitchsia

Ephedra spp.= Mormon tea

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Mormon tea

Canyonlands NP, UT

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Gymnosperms: Coniferophyta

Key characteristics:

Needle-like or scale like leaves

Thick cuticle

Recessed stomata

Resin

Cones

female

gametophyte

eggs

pollen

tube

haploid (n)

diploid (2n)

5

7

3

4

1 2

6

mature

sporophyte scale of a

female cone

scale of a

male cone

sperm

nucleus

embryo

seed

seedlings

female cone

male cone

spore-forming

cell

ovule

FERTILIZATION

MEIOTIC CELL

DIVISION IN

MALE SCALE

MEIOTIC CELL

DIVISION IN

FEMALE SCALE

Male cone

scales give rise to

pollen; each female

cone scale contains

two ovules

Pollen

is liberated

and carried

by the wind

Pollen lands

on the scale of a

female cone and

a pollen tube

begins to grow

As the pollen tube grows,

meiotic cell division in the ovule

leads to development of the

female gametophyte

When the pollen tube

reaches an egg within

the female gametophyte,

a sperm nucleus moves

through the tube and

fertilization occurs

The fertilized egg

develops into an embryo,

which is encased in a seed

The seed

germinates and the

embryo develops into

a sporophyte tree

Life Cycle of the Pine

Fig. 21-11

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Angiosperm specific adaptations

Unlike other plants they have: Flowers

Double fertilization

Fruit

What are the advantages of flowering?

Discuss this question in groups

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Angiosperms: the Flowering plants

Why do plants have flowers?

Enlists partnerships with insects and other animals

Less inbreeding

Higher probability the pollen will reach the right plant

They don’t have to produce as much pollen

Double fertilization 1. Two pollen nuclei enter ovule

2. One fuses with the egg to form the zygote

3. The other fuses with 2 central cell nuclei to become the endosperm (3n), food for the zygote

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Fruit development

Becomes the fruit! Becomes the seed!

anther

Flower ---> Fruit Progression

Apple

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Fruit: Form and Function Dispersal Mechanisms

Wind Animals

Maple seed

Milkweed Fleshy fruit

Acorn

Trends through Time

Gymnosperms

Angiosperms

Lycophytes

Pterophytes

Bryophytes

Ancestral Derived

Activity: Arrange the taxa below along the time

continuum, include shared, derived traits and examples

for each

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Trends through Time Ancestral Derived

Bryophytes

True mosses

Liverworts

Hornworts

Lycophytes Pterophytes

Club mosses:

Selaginella

Lycopodium

Whisk ferns

Horsetails

True Ferns

Gymnosperms Angiosperms

Conifers

Ginkophyta

Cycads

Gnetophyta

Monocotyledons

(monocots)

Dicotyledons

(dicots)

Non-vascular Seedless vascular

Seeds & Vascular

No Fruit Fruit

Trends through Time Ancestral Derived

Bryophytes

Gametophyte

dominant

Sperm - water

Pores

Waxy cuticle

Lycophytes Pterophytes

Sporophyte

dominant

Sperm - water

Vascular

tissue

Stomata

Stems

Leaves

Roots

Strobilus

Waxy cuticle

Sporophyte

dominant

Sperm - water

Vascular

tissue

Stomata

Stems

Leaves

Roots

Sori

Waxy cuticle

Gymnosperms Angiosperms

Sporophyte

dominant

Sperm-no water

Vascular tissue:

xylem-tracheids

Stomata

Woody stems

Seeds & Pollen

Waxy cuticle

Sporophyte

dominant

Sperm-no water

Vascular tissue

xylem-tracheids

phloem-seive

tube members

Seeds & Pollen

Flowers & Fruits Double fertilization

Waxy cuticle

Stomata

Non-vascular Seedless vascular

Seeds & Vascular

No Fruit Fruit