2Pollination Definition: transfer of pollen from stamen to stigma Contrast with herbivory. Animals eating plant products but:1) Most pollinators winged2) If insects, adults involved directly and not larvae3) Few mammals involved (except bats)
4Life Cycle Example of sporic meiosis: Gametophytes make gametes BY MITOSISZygote grows into diploid individual called sporophyteSporophyte makes meiospores BY MEIOSISTwo bodies in one cycle: alternation of generations
6Life CycleOverview:Fertilization: union of sperm with egg to form zygote
7Floral variation Parts may be fused Example, petals fused to each other.Snapdragon flower
8Floral variation Parts may be fused Example, petals fused to each otherLike parts fused: connation (ex., petals to petals)Unlike parts fused: adnation (ex., stamens to petals).Snapdragon flower
9Floral variationFusing of petals can form floral tube (nectar made at bottom)Only long-tongued pollinators can reach it.Anisacanthus (Acanthaceae) flower
10Floral variationFlowers with both stamens and pistils: perfect flowersAnotherkind ofperfection….
11Floral variationFlowers with both stamens and pistils: perfect flowersSome flowers imperfect. Either pistillate (have pistil) or staminate (have stamens).Pistillate flowers of SagittariaStaminate flowers of Sagittaria
12Floral variationNote: some species make pistillate flowers and carpellate flowers on separate individualsThis termed dioecy (MUST outcross to reproduce sexually)Monoecy is when both sexes on same individual.
13Floral variation Example of dioecious species: Persimmon (Diospyros) Persimmon fruitsExample of dioecious species: Persimmon (Diospyros)PistillateflowerStaminateflower
14Floral variationSome flowers are missing one or more sets of basic parts: incomplete flowersNote that all imperfect flowers are therefore incomplete!
15Floral variation Floral symmetry: Radial: can be divided into similar halves by several planes
16Floral variation Floral symmetry: Radial: can be divided into similar halves by several planesBilateral: can be divided into mirror images by 1 plane.
17Floral variation Ovary position Superior ovary: other parts attach below ovary (hypogynous: “hypo-” =below, “gyn-” =female)
18Floral variationExample of superior ovary in a lily flower (ovary is E)
19Floral variation Ovary position Perigynous flower: ovary superior, but cup formed of fused sepals, petals, stamens around it.
20Floral variation Ovary position Inferior ovary: other parts attach above ovary (epigynous: “epi-”=above, “gyn-”=female).
21Floral variationExample of inferior ovary: squash flower (this one is pistillate).Ovary
22Floral variationSome flowers assembled into groups of flowers: inflorescenceSpecial inflorescence type: headExample, sunflower and its relativesRay flowers have large fused petals (corollas fused), disk flowers small and crowded.ray flowersdiskflowers
23Floral variation Flowering dogwood (Cornus florida) Inflorescence: white structures are modified leaves (bracts) that act like petals.Closeup showing individualgreenish flowersInflorescence
24PollinationWhy flowers so varied? Many form mutualism with animals to achieve pollination
25Mutualism ExceptionsSome flowering plants are wind pollinated (anemophily)Some are water pollinated (hydrophily)Small, greenishgrass flowers
26Pollination as Mutualism Most flowering plants are pollinated by animalsThis usually viewed as mutualism (where both species benefit)Plant gets pollen transferredAnimal gets “reward”
27Rewards Pollen: high in protein Also has lipids, minerals, starch Can be renewed by:sequential anther dehiscence (multiple stamens)poricidal anthers (buzz pollination)
28RewardsNectar: sugary fluid produced by nectar glands (nectaries) in flower10-60% mono- or disaccharidesMay have amino acids too (butterfly flowers)Renewable reward!
29RewardsOils/Resins: some used as construction materials, “cologne” (male solitary bee uses oil as female attractant), food for larvae (Krameria)Edible petals (pineapple guava: New Zealand)Krameria wax gland: wasp food!
30Pollination Benefits of animal pollination for plant 1) Directed dispersal of pollen. Can get delivered from stamen to stigma with less wasteFloral cues and attractants:Color and shapeScentWarmth (thermogenic plants: rare)Skunk cabbage
31Pollination Benefits of animal pollination for plant 1) Directed dispersal of pollen.This aided by learning of floral visitors: decreases “handling time”Fosters “floral constancy” (visiting single species on foraging trip) by beesBumblebeevisits totouch-me-not
32Pollination Benefits of animal pollination for plant stigma style 2) Style of flower as “selective racetrack”stigmastyleovary2 ovules
33Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Keep in mind that 1 pollen grain can fertilize 1 ovuleSuppose 5 pollen grains arrive on stigmaPollen grainsstigmastyleovary2 ovules
34Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Keep in mind that 1 pollen grain can fertilize 1 ovuleSuppose 5 pollen grains arrive on stigmaStart to make pollen tubesHow many can fertilize an ovule?Pollen grainsstigmapollen tubesstyleovary2 ovules
35Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Keep in mind that 1 pollen grain can fertilize 1 ovuleSuppose 5 pollen grains arrive on stigmaStart to make pollen tubesHow many can fertilize an ovule?2! First 2 to arrive!Rest? LOSERS!Pollen grainsstigmastyleovary2 ovules
36Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Pollen tubes are haploid (1n)Haploid means only 1 allele (gene version) for every traitPollen grainsstigmastyleovary2 ovules
37Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Pollen tubes are haploid (1n)Haploid means only 1 allele (gene version) for every traitIf an allele is recessive, then it will be expressed (can’t be masked by another, dominant allele)Pollen grainsstigmastyleovary2 ovules
38Pollination Benefits of animal pollination stigma style ovary 2 ovules 2) Style of flower as “selective racetrack”Pollen tubes are haploid (1n)Haploid means only 1 allele (gene version) for every traitIf an allele is recessive, then it will be expressed (can’t be masked by another, dominant allele)So, fittest (fastest) pollen grains mateInferior genes don’t get passed to offspring.Pollen grainsstigmastyleovary2 ovules
39Pollination Style of flower as “selective racetrack” Is there evidence that this works?Example, Coyote melonGourd growing in U.S. deserts.
40Pollination Style of flower as “selective racetrack” Study done in 2000 showed that:1) takes 900 pollen grains to fully pollinate flower
41Pollination Style of flower as “selective racetrack” Study done in 2000 showed that:1) takes 900 pollen grains to fully pollinate flower2) 1 pollinator visit puts 650 grains/stigma. By 2 hours, >4000 grains deposited on stigma
42Pollination Style of flower as “selective racetrack” Study done in 2000 showed that1) takes 900 pollen grains to fully pollinate flower2) 1 pollinator visit puts 650 grains/flower. By 2 hours, >4000 grains deposited on stigma3) Seeds produced from over-pollinated flowers produced more vigorous seedlings (compared to seeds from flowers with <900 pollen grains on stigma).
43OutcrossingMajor benefit of sexual reproduction: generate genetic variationThis enhanced by mating with others (outcrossing)
44Outcrossing How to favor outcrossing: 1) Dioecy Bet hedging! Some selfing canoccur if no cross pollinationImperfect flowers
45Outcrossing How to favor outcrossing: 2) Floral morphology Heterostyly: Distyly and tristyly
46Outcrossing How to favor outcrossing: 2) Floral morphology Heterostyly: Distyly and tristyly
47Outcrossing How to favor outcrossing: 3) Floral phenology ProtandryHow to favor outcrossing:3) Floral phenologyProtandry: anthers dehisce firstProtogyny: stigma becomes receptive first
48Outcrossing How to favor outcrossing: 4) Self-incompatibility: prevents germination of self pollen or slows self pollen tube growth
49Specialization May be learned May be species-specific Monolecty: Flowers of 1 plant species visitedOligolecty: Flowers of few plant species visitedPolylecty: Flowers of many plant species visited
50Specialization Benefits of taxonomic specialization Better service: can match phenology of plant/pollinatorDecrease competition (must match flower/pollinator traits)Plant: Minimize stigma clogging with heterospecific pollen
51Pollination syndromes Disclaimer: Note that we must make broad generalizations and exceptions exist to most statements!
52Pollination syndromes Bee pollination: MelittophilyBees are:intelligent, agilevisual animals: good eyesight (including UV light)good smellers (good sense of smell)day-active
53Pollination syndromes Bee pollinationBee pollinated flowers are:Colorful (usually not red)Have landing platform: place where bee can land on flowerMildly fragrant.
54Pollination syndromes Bee pollinationBee pollinated flowers:May have nectar guides: patterns of lines or dots that can guide bee to rewardSometimes these only visible in UV light (which bees see).Orchid flowerwith nectarguides (lines)on petalsPetals in visible light(top) and UV (bottom)
56Pollination syndromes Beetle pollination: CantharophilyBeetles are:ClumsyHave poor visionDumb(er)Active during the day (many flower-visiting ones).
57Pollination syndromes Beetle pollinationBeetle pollinated flowers are:Relatively large or grouped into large inflorescencesLight coloredSmelly (fruity or spicy smell)Inflorescence ofXanthosoma withbeetle from itDogwood inflorescence
58Pollination syndromes Bird pollination: OrnithophilyBirds are:agilelong-beakedvisual: see red colors wellpoor “smellers”
59Pollination syndromes Bird pollinationHummingbirds (native to Americas) can hover: don’t need to land to access flower rewards.
60Pollination syndromes Bird-pollinated flowers are:red or orangehave nectar hidden by long floral tubelittle or no fragranceno landing platformAnisacanthus(Acanthaceae) flowerAloe
61Pollination syndromes Bird pollination: not always by hummingbirdsOther birds from other areas:Sunbirds (Africa/Asia)Honeycreepers (Hawai’i).Golden-wingedsunbirdIiwi (a honeycreeper)Crested honeycreeper
62Pollination syndromes Butterfly pollination: PsychophilyButterflies have: good vision, good sense of smell, long coiled tongue. Must land on flower to visit it (can’t hover).coiled tonguetongue extended
63Pollination syndromes Butterfly-pollinated flowers:Color varies (blue, yellow, orange)Landing platform presentNectar at bottom of floral tubePlumbago flowersPhlox flowers
64Pollination syndromes Fly pollination: MyophilyFlies have good sense of smell, especially flesh fliesAttracted to rotting meat (lay eggs in meat, larvae are maggots).
65Pollination syndromes Fly-pollinated flowers: SapromyophilySmell like rotting meatLook like rotting meat (dark red, purple)Offer no reward: flies fooled by flower.Stapelia flower
66Fly flower story: Rafflesia Ex, Rafflesia of SumatraRoot parasiteFlower is only above-ground part.
67Fly flower story: Rafflesia Ex, Rafflesia of SumatraLargest single flower on Earth.
68Pollination syndromes Fly pollinationLargest inflorescence is made by fly-pollinated plantCorpse-flower.Inside view
69Pollination syndromes Bat pollination: ChiropterophilyBats are flying mammalsNocturnalEyesight good but echolocateGood sense of smellAgile, can hover when visiting flower.
70Pollination syndromes Bat pollinationBat-pollinated flowersOpen at nightProduce lots of pollen and nectar as rewardsWhite or light-coloredFragrant (sweet odor)May be pendant (hang down from branches).Parkia flowers
71Pollination syndromes Bat pollinationBat-pollinated flowersMay also be made on tree trunks (tropics): CaulifloryEx, cannonball tree of South America
72Pollination syndromes Bat pollination: Mainly a tropical phenomenonIn U.S., saguaro cactus is one of few bat-pollinated species.Saguaro cactusSaguaro flowers
73Pollination syndromes Moth pollination: PhalaenophilyMoths have:Poor vision (nocturnal)Excellent sense of smellLong coiled tongue.
74Pollination syndromes Moth pollinationMoths:Some (hawkmoths) can hover when visiting flowers.Hawkmoth
75Pollination syndromes Moth pollinationMoth-pollinated flowers:Open at nightSweet fragranceWhite or light-coloredNectar in tube.
76Pollination syndromes Interesting moth story: nectar spurNectar spur is long pouch, at bottom of which is nectarMoth uses long tongue to reach nectarNectar spurson columbine
77Pollination syndromes Interesting moth story: nectar spurNectar spur is long pouch, at bottom of which is nectarMoth uses long tongue to reach nectarOnly if tube is longer than tongue will moth have to push into flower far enough to pick up pollenSo, long spurred flowers reproduce better.
78Pollination syndromes Which leads to longer moth tongues to reach all of the nectar in the longer tubesWhich leads to longer tubes......
79Pollination syndromes Which leads to longer moth tongues to reach all of the nectar in the longer tubesWhich leads to longer tubes......Some moth-pollinated orchids with long nectar spurs (almost one foot long!)Moth has extremely long tongue!
81Pollination syndromes Can read more in magazine for Gene Simmons fans.Gene Simmonsfrom KISS
82Sexual Mimics Flowers that mimic female bees or wasps Look like femalesSmell like females: chemical mimicry. One study showed flower more attractive than real female!!Sexual mimicorchids
83Pollination syndromes Sexual mimicsMales attempt to mate, pick up pollen, then fly to another flower and repeat processNo reward supplied!.A male wasp “mating”with an Ophrys flower(how embarrassing...)
84Pollination syndromes Another trick flowerGrass pink orchid (Calopogon): grows in pitcher plant bogs in SE USMakes fake stamens on petal.Plant ecologyclass in bogCattleya orchid (flowermade right side up)Calopogon orchid (flowermade upside down!)