Pollination

Defn.?

Pollination• Def’n: transfer pollen from stamen to stigma

Carpel = pistil

Life Cycle• Sporic meiosis:

– Gametophytes make gametes BY MITOSIS– Sporophyte makes meiospores BY MEIOSIS

• Two bodies/one cycle: alternation of generations

Spore: cell grows into organismw/o joining withanother cell

Life Cycle• Overview:

Life Cycle• Overview:• Fertilization: union

sperm with egg to form zygote

Floral variation• Parts may be fused

– Like parts: connation (ex., petals to petals)

– Unlike parts: adnation (ex., stamens to petals)

Snapdragon flowerAnisacanthus (Acanthaceae) flower

Floral variation• Flower with stamens and pistil: perfect flower

Anotherkind of perfection….

Floral variation• Some flowers imperfect. Pistillate or staminate

Staminate flowers SagittariaPistillate flowers Sagittaria

Floral variation• Pistillate & staminate flowers on separate individuals:

Dioecy (MUST outcross)– Monoecy: both sexes on same individual.

• Flower missing one or more sets parts: incomplete flower– All imperfect flowers incomplete!

Who am I?

Floral variation• Some flowers grouped:

inflorescence– Special type: head. Ex,

sunflower– Often: ray & disk flowers

diskflowers

ray flowers

Pollination as Mutualism• Most flowers pollinated by animals• Exceptions:

– wind pollinated (anemophily)– water pollinated (hydrophily)

• Usually mutualism (+,+)– Plant: pollen transferred– Animal: “reward”

Animal Reward…

Rewards• Pollen: high protein

– Also lipids, minerals, starch

• Renewed by:– sequential anther dehiscence (multiple stamens)– poricidal anthers (buzz pollination)

Rewards• Nectar: sugary fluid

produced by nectaries– 10-60% mono- or

disaccharides– amino acids too

(butterfly flowers)

• Renewable reward!

Plant benefit?

Pollination• Benefits animal pollination (to plant)

– 1) Directed dispersal pollen: Floral cues and attractants

– Learning decreases “handling time”– “Floral constancy:” visit single species on foraging

trip

Bumblebeevisits to touch-me-not

Pollination• Benefits of animal pollination

– 2) Style as “selective racetrack”– 1 pollen grain fertilizes 1 ovule

stigma

style

ovary

2 ovules

Pollen grains

Pollination• Benefits of animal pollination

– 2) Style as “selective racetrack”– Pollen tubes – How many can fertilize an ovule?

stigma

style

ovary

2 ovules

Pollen grains

pollen tubes

Pollination• Benefits of animal pollination

– 2) Style as “selective racetrack”– Pollen tubes haploid (1n)– 1 allele for every trait

stigma

style

ovary

2 ovules

Pollen grains

Pollination• Benefits of animal pollination

– 2) Style as “selective racetrack”– So, fittest (fastest) pollen grains

mate

stigma

style

ovary

2 ovules

Pollen grains

Pollination• Evidence?• Coyote melon: U.S. deserts

– Seeds from over-pollinated flowers produce more vigorous seedlings

Outcrossing• Major benefit sexual reproduction is ___________• Enhanced by mating with others (outcrossing)

How favor Outcrossing?

Outcrossing• Favor outcrossing:• 1) Dioecy

OutcrossingFavor outcrossing:

• 2) Floral morphology• Heterostyly: Distyly and tristyly

Outcrossing• Favor outcrossing:• 3) Floral phenology• Protandry: anthers dehisce first• Protogyny: stigma becomes

receptive first

Protandry

Outcrossing• Favor outcrossing:• 4) Self-incompatibility: prevent germination self pollen

or slow self pollen tube growth

Pollinator Specialization• May be learned

• May be species-specific– Monolecty: Flowers of 1 plant species visited– Oligolecty: Flowers of few plant species visited– Polylecty: Flowers of many plant species visited

Pollination syndromes

•Disclaimer: We make broad generalizations and exceptions exist to most statements!

Pollination syndromes• Bee pollination• Bees:

– intelligent, agile– good eyesight (including UV light)– good smellers – day-active

Leafcutter bee Bumble bee

Halictid bee

Pollination syndromes• Bee flowers:

– Colorful (not red)– Landing platform: where bee lands on flower– Often nectar guides: patterns help bee orient

Petals in visible light(top) and UV (bottom)

Pollination syndromes• Moth pollination• Moths:

– Poor vision (nocturnal)– Excellent smellers– Long coiled tongue– Some (hawkmoths) hover

Pollination syndromes• Moth pollination• Moth-pollinated flowers

– Open night– Sweet fragrance– White/light colored– Nectar in tube

• Nectar spur story

Pollination syndromes• Angraecum orchid (Madagascar)

Nectar spur almost1 foot long!

Pollination syndromes• Angraecum orchid from Madagascar.

Nectar spur almost1 foot long!

Tongue…

Pollination syndromes• Tongue Magazine, Gene

Simmons fans.

Gene Simmonsfrom KISS

Family Guy: “Kiss saves Santa”

Biotic Pollination• Mutualism: (+,+) interaction• Do cheaters prosper??• Sometimes…..

Pollination syndromes• Flesh fly pollination• Lay eggs in meat

Pollination syndromes• Some fly-pollinated flowers

– No reward: flies fooled.

Stapelia flower

Pollination syndromes• Sexual mimics: Males

attempt to mate (pseudocopulation)

• No reward supplied

A male wasp “mating”with an Ophrys flower(how embarrassing...)

Pollination syndromes• Another trick flower• Grass pink orchid (Calopogon): pitcher plant bogs SE

US• Fake stamens on labellum

Calopogon orchid (flowermade upside down!)

Cattleya orchid (flowermade right side up)

Biotic Pollination• Do cheaters prosper?? Floral robbers!

Cool robbers…

Biotic Pollination• Floral Robber: Remove rewards (nectar, pollen) but

do not pollinate• Ex, snapdragon• Is robbing bad for plant?

Biotic Pollination• Do cheaters prosper?? • Yucca moth story• Yucca: Agave family

– Ex, Yucca filamentosa

Biotic Pollination• Pollination by yucca moth: Behavior

• Question: What do you call a female yucca moth?

Biotic Pollination• Question: What do you call a female yucca moth?• A pistil-packing momma……….

Granny Glock

Biotic Pollination• What if moth cheats (lays too many eggs?)