Plant Diversity II: Seed Plants

Home , Gnetophyta, Moss

5/21/2014

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, Kettles, MA, SR, Browning, TS Prince, and SW Horstman. 1997. Triazine herbicide exposure and breast cancer  including low birth weights, incidence: An ecologic study of Kentucky counties. Environmental Health Perspectives 105(11):1222-1227.  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/]

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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?

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?

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.

water

Moss fertilization Pollen grains

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

Gymnosperms: Cycadophyta

Cycads  Palm-like plants, but have cones for reproduction

 Tropical

 Endangered by poaching and a 23% of 305 extant black market species endangered, 15% vulnerable

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Gymnosperms: Gnetophyta Ephedra Welwitchsia Gnetum

Temperate regions Namibia Old and New except Australia World Tropics • Flower-like structures

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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

Life Cycle of the Pine

scale of a male cone

MEIOTIC CELL DIVISION IN ovule MALE SCALE

spore-forming 1 Male cone 2 Pollen cell male cone scales give rise to is liberated pollen; each female and carried 3 Pollen lands cone scale contains by the wind on the scale of a two ovules female cone and a pollen tube MEIOTIC CELL mature begins to grow scale of a DIVISION IN sporophyte female cone FEMALE SCALE

female cone female gametophyte

7 The seed 4 As the pollen tube grows, germinates and the meiotic cell division in the ovule embryo develops into leads to development of the a sporophyte tree female gametophyte seedlings eggs pollen 6 The fertilized egg 5 When the pollen tube tube develops into an embryo, reaches an egg within which is encased in a seed the female gametophyte, a sperm nucleus moves through the tube and seed fertilization occurs embryo

FERTILIZATION

sperm haploid (n) nucleus diploid (2n) 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

anther

Becomes the seed! Becomes the fruit!

Flower ---> Fruit Progression

Apple

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Fruit: Form and Function Dispersal Mechanisms

Wind Animals

Acorn

Maple seed

Fleshy fruit Milkweed

Trends through Time Ancestral Derived

Activity: Arrange the taxa below along the time continuum, include shared, derived traits and examples for each

Gymnosperms Bryophytes Lycophytes

Angiosperms Pterophytes

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Trends through Time Ancestral Derived

Seeds & Vascular Non-vascular Seedless vascular No Fruit Fruit

Bryophytes Lycophytes Pterophytes Gymnosperms Angiosperms True mosses Club mosses: Whisk ferns Conifers Monocotyledons Liverworts Selaginella Horsetails Ginkophyta (monocots) Hornworts Lycopodium True Ferns Cycads Dicotyledons Gnetophyta (dicots)

Trends through Time Ancestral Derived

Seeds & Vascular Non-vascular Seedless vascular No Fruit Fruit

Bryophytes Lycophytes Pterophytes Gymnosperms Angiosperms Gametophyte Sporophyte Sporophyte Sporophyte Sporophyte dominant dominant dominant dominant dominant Sperm - water Sperm - water Sperm - water Sperm-no water Sperm-no water Pores Vascular Vascular Vascular tissue: Vascular tissue Waxy cuticle tissue tissue xylem-tracheids xylem-tracheids Stomata Stomata Stomata phloem-seive Stems Stems Woody stems tube members Leaves Leaves Seeds & Pollen Seeds & Pollen Roots Roots Waxy cuticle Flowers & Fruits Strobilus Sori Double fertilization Waxy cuticle Waxy cuticle Waxy cuticle Stomata