FLOWERS !

Land Plants Review Moist Dry environments 1) Swimming sperm (club moss, horsetails, ferns) 2) Airborne pollen + swimming sperm (few gymnosperms) 3)Airborne pollen (gymnosperms & angiosperms) 4) Animal borne pollen (angiosperms)

Brief History of Land Plants ~470 MYA 1st Land Plants 300 MYA 500 species-club mosses, horsetails, ferns, gymnosperms 150 MYA 3,000 species mostly gymnosperms 90 MYA 22,500 species—mostly angiosperms Today 300,000 species—mostly angiosperms

5 STAGES OF LAND PLANT EVOLUTION

5 STAGES OF LAND PLANT EVOLUTION

5 STAGES OF LAND PLANT EVOLUTION

5 STAGES OF LAND PLANT EVOLUTION

5 STAGES OF LAND PLANT EVOLUTION

What do you conclude from these data? Why have angiosperms been so successful compared to gymnosperms? What do you conclude from these data?

Why have angiosperms been so successful? Adaptations to dry land Rapid reproduction cycle & Early maturity Flowers with Well protected and well-nourished seeds Efficient seed dispersal mechanisms Efficient pollination Recall the evolution of sperm transfer Animals especially Insects Water Air (wind)

But first animals on land were arthropods. First insect fossils ~ 470 mya at the same time as the first land plants colonized land. First flying insects ~325 mya. Major diversification of insects (bees, flies, butterflies & moths) ~150 mya occurred along with the radiation of flowering plants

Phylum Angiosperms ( Flowering Plants) Two major classes Monocotylendonae Eudicotyledonae

Types of Flowers Complete Flowers (Perfect Flowers)= flowers with all of the usual male and female parts

Double Fertilization Triploid Endosperm (3n)

Fruit Formation

SEEDS Eu

Types of Flowers Cont’. Incomplete Flowers (Imperfect Flowers) = Flowers with one or more basic parts missing e.g. Pistillate flowers have only female pistil e.g. Staminate flowers have only male stamen

Corn with incomplete flowers

Flower Symmetry Radial Symmetry (Circular & disk-like) Line through the center in any direction forms identical halves. (Attracts general pollinators)

Tallest Flower Has Radial symmetry “Corpse Flower” Amorphophallus titanum

Largest Blossom Rafflesia arnoldii

Flower Symmetry Bilateral Symmetry Line through the center in one direction can produce mirror images. (These flowers attract specific pollinators)

Composite Flowers. = Flowers grouped together into Composite Flowers = Flowers grouped together into clusters to produce a showy display

Head of a sunflower

Pollination Wind Pollination –earliest pollination Characteristics of wind pollinated flowers Unisexual flowers—encourages outbreeding Monoecious= corn, oak, melons Dioecious= willows, poplars, maples, spinach, asparagus

Wind pollination in angiosperms (grasses) Characteristics of wind pollinated flowers: Small inconspicuous Without petals No scent or nectar Large quantity of pollen produced

Animal Pollination Many types of animals involved: 85% of flowers pollinated by insects (bees, butterflies, beetles, flies, ants); they get pollen and nectar. Birds and a few small mammals especially bats Less pollen needs to be produced than in wind pollination Flowers are bisexual—increases efficiency

Generalist vs. Specialist Strategies Generalist Flowers—attract many pollinators Specialist—attracts only one pollinator Disadvantage –flower and pollinator are dependent upon one another Benefit for plant—prevents waste of pollen & nectar for inefficient pollination Benefit for pollinator—monopoly of food source

The Co-Evolution of Flowers and their Pollinators

Attracting Pollinators Color & UV & electric patterns Nectar guides—lines of color that “guide” the pollinator to the nectaries (glands that produce the sugar water) Fragrance—scent glands Sex

Bee Flowers Flowers open during day Bees visit many species Some flowers are specialized only for bees

Buzz Pollination Some bee species grab tubular anthers & vibrate flight muscles and shake the pollen out of pore at the end.

Nectar Guides

Ultraviolet Light Patterns Dandelion

Ultraviolet Light Patterns Silverweed

Sex Flower that mimics female bees by color and scent to attract male bees. Bee orchid

Bird Flowers (e.g. hummingbird) Color red or orange Produce lots of nectar Flowers large and shaped as tubes or funnels, cups or flasks. Lack odor

Bat Flowers Nocturnal flowers Pale color Strong scent Bats with long Nose and tongue. Some hover, some don’t

Fly Flowers Flies are second most common pollinators Smell is primary attractant Color yellow, green, white, can be mottled and look & smell like rotting meat

Butterfly Flowers Diurnal Bright colors Smell modest Petals fused into long tubes for proboscis

Moth Flowers Flowers are nocturnal Pale color Strong sweet smell Petals fused into long tubes for long proboscis

The case of the hawk moth and the iris

Hawkmoths & the S. African Iris Hawkmoths are important pollinators! S. African Iris produces nectar inside a flower tube as a reward for pollinators. The ‘flower tube’ can vary in length. How does the Hawkmoth pollinate?... Open Source Photo Credit: https://commons.wikimedia.org/wiki/File:Kaibara87_-_Hummingbird_Hawk-moth_(by).jpg

How do hawkmoths pollinate S. African iris? Hawkmoths stick their long tongues inside the flower tube to collect the nectar. When their tongue is inside, the the pollen from the stigma sticks to the head of the hawkmoth. When they visit a new flower, they transfer the pollen from previous plant visits. Tongue length Open Source Photo Credit: https://commons.wikimedia.org/wiki/File:Hummingbird_Hawk-moth.jpg Flower tube length

Distribution of flower tube length

Distribution of moth tongue lengths

Question : what kind of selection do you think hawkmoth tongue length will have on flower tube length? A B C Short flower tube length Long

Other Pollinators: Mouse