Pollination Biology Pollination Biology of Orchidsof Orchids

Mark Whitten

Florida Museum ofNatural History

University of Florida

Ernst Haeckel, 1904Kunstformen der Natur

Orchid DiversityOrchid Diversity

Orchids are the largest family of flowering plantsOrchids are the largest family of flowering plants----~ ~ 10% of angiosperms10% of angiosperms~25,000 species described so far (Kew Checklist of ~25,000 species described so far (Kew Checklist of Orchids, RBG Kew)Orchids, RBG Kew)New species being described weeklyNew species being described weeklyHighest diversity in poorlyHighest diversity in poorly--explored tropicsexplored tropics

Number of New Orchid Species Described Each Year

0

100

200

300

400

500

60019

78

1980

1982

1984

1986

1989

1991

1993

1995

1997

1999

2001

Source: Cribb, P. 2005. Just how many orchids are there? Proceedings of the 18th WOC

Orchids are HYPERDIVERSE in Orchids are HYPERDIVERSE in montane tropicsmontane tropics

Telipogon spp. Of Ecuador: C.H. Dodson

Why are orchids so diverse?Why are orchids so diverse?

Inhabit all continents except poles; Inhabit all continents except poles; geologically old family (90geologically old family (90--100 MY ?)100 MY ?)Orchids exploit many different animals as Orchids exploit many different animals as pollinatorspollinatorsPollination relationships often highly speciesPollination relationships often highly species--specificspecific----reproductive isolationreproductive isolationHave obligate Have obligate mycorrhizalmycorrhizal associationsassociationsPredominately epiphytic (new niches?)Predominately epiphytic (new niches?)

Habitat diversity fosters biological Habitat diversity fosters biological diversitydiversity

Teagueia spp. : Lou Jost21 new species in 2 years in 80 sq. miles

Ecuador: Pastaza valley

Precision pollinationPrecision pollination

Dichaea trulla

Reproductive IsolationReproductive IsolationHow can sympatric, How can sympatric, interfertileinterfertile species species live together without live together without hybridizing?hybridizing?Highly specific Highly specific pollinators prevent pollinators prevent hybridization, and hybridization, and avoid wasting pollenavoid wasting pollenPrecise pollen Precise pollen placement might placement might prevent prevent hybridizationhybridization

Aspasia epidendroides

Floral morphology

3 sepals2 lateral petals + lipColumn (fused male

+ female parts)Ovary + pedicel

Anther cap

Stigma

ViscidiumPollinia

Pollinarium

Pollinia

Stipe

Viscidium

Pollinated stigma

Pollination rewardsPollination rewards

Nectar (insects, birds)Nectar (insects, birds)PollenPollen----No!No!Floral fragrances (male Floral fragrances (male euglossineeuglossinebees)bees)Resins (used by bees for nest building)Resins (used by bees for nest building)Oils (used by Oils (used by anthophoridanthophorid bees to feed bees to feed larvae)larvae)

Pollination syndromesPollination syndromes

A bit simplistic, but useful and often A bit simplistic, but useful and often predictivepredictiveBased upon reward offered and upon Based upon reward offered and upon the behavior and morphology of the behavior and morphology of pollinatorspollinatorsFloral morphology, color, fragrance may Floral morphology, color, fragrance may allow prediction of probable pollinatorsallow prediction of probable pollinators

Dendrobiumcuthbertii Bird pollination

-Nectar reward present or absent-Present in Neotropical and

Paleotropical orchids

Masdevallia rosea Fernandezia subbiflora Maxillaria sophronitis

Masdevallia rosea

Fernandezia subbiflora

Hexisea bidentata

Pollination of Disachrysostachya by Sunbirds in SouthAfrica

S.D. Johnson and M. Brown. 2004.Transfer of pollinaria on bird’s feet:A new pollination system in orchids.Plant Systematics and Evolution

Pollinaria are attached to bird’sfeet!

Epidendrums can be taxonomically confusing…..

Butterfly pollinationButterfly pollination

Epidendrum hybrid swarm, Hollin road, Ecuador

….But especially confusing when they hybridize

Comparettia macroplectron

HawkmothHawkmoth pollinationpollination

Amesiellaphilippenensis

Angraecumrutenbergianum

Aerangis sp.

Dendrophylax fawcettii

Angraecum sequipedale &Xanthopan morganii

Epidendrum lacustreEcuador

Disa draconis andtanglewing fly

Johnson, S.D. and K. E. Steiner. 1997. Long tongued flypollination and the evolution of spur length in Disadraconis. Evolution 51:45-53.

Pollen deceitPollen deceit

Calopogonpulchellus

PseudopollenReward or Deceit?

Maxillaria with pseudopollenon lip

Male Male EuglossineEuglossine beebeepollinationpollination

Ca. 250 species in Ca. 250 species in NeotropicsNeotropicsOnly Only malesmales collect floral fragrance collect floral fragrance chemicals and store them in special chemicals and store them in special hind hind tibialtibial organsorgansProbably use compounds in mating Probably use compounds in mating behavior (sexual selection)behavior (sexual selection)

Long tongues

Female Eufriesea

Pollen Basket

Stinger

Eulaema meriana(male; no stinger!)

Euglossa dodsoni and

Eulaema meriana

Tarsal brush

Hind tibiaCross-section

Eulaema maleCourtship display on tree trunk

Clowesia warsczewicziiand Eulaema meriana

Catasetum expansum

Catasetumpollinarium

CatasetumFemale flowerCross section

Cycnoches lehmannii& Eulaema cingulata

CycnochesMale flower

Cycnoches densiflorumFemale/hermaphroditeflowers

Stanhopeacostaricensis

Eulaema meriana withStanhopea pollinarium

Sievekingia butcheri

Paphinia neudeckeri

Gongora tricolorWith Euglossa cyanura

Photo: Kerry Dressler

Gongora hirtzii

Gongora aff. quinquenervis with crystals ofmethyl-p-methoxycinnamate

Mormodes cartoniiMormodes cartonii

Mormodespollinarium

Euglossa viridissima:Invading south Florida!

Pollinating cultivated Lycaste in Ft. Lauderdale gardenPhoto: Bob Pemberton

Oil reward flowersOil reward flowers

Oils (Oils (triacyltriacyl glyceridesglycerides) produced on ) produced on surface of flowers, often in specialized surface of flowers, often in specialized glandsglands---- elaiophoreselaiophores..Oils are collected by female Oils are collected by female anthophoridanthophoridbees; used to provision nest (food for bees; used to provision nest (food for larvae)larvae)Many orchids mimic Many orchids mimic MalpighiaceaeMalpighiaceae

CyrtochilumWith oil gland(elaiophore)

Sigmatostalix sp.

OIL GLANDS & MIMICRY IN THE ONCIDIINAE:SIGMATOSTALIX & TOLUMNIA

Ornithocephalus sp.

Ornithocephalus sp.

Wax or resin rewardWax or resin reward

Collected and used by female bees for Collected and used by female bees for nest constructionnest constructionFound in Found in MaxillariaMaxillaria and and CymbidiumCymbidium; ; poorly studiedpoorly studied

Resin reward: collected by female bees for nest construction

Maxillaria notylioglossa

Waxy resin crystals

Maxillaria proboscidea

RESIN

Resin deceit?Resin deceit?

Many Maxillaria speciesappear to produce resin, but “resin” is simply a shiny callus on lip.

Deceit of resin-collectingfemale bees?

Sexual deceptionSexual deception

Based on floral fragrance mimicry of Based on floral fragrance mimicry of sexual pheromones of pollinatorssexual pheromones of pollinatorsUsually visual, tactile mimicry, tooUsually visual, tactile mimicry, tooHas evolved repeatedly in several Has evolved repeatedly in several different orchid groupsdifferent orchid groups

Sexual deceit doesn’t have to be perfect--just enough to be convincing!

Chiloglottis formicifera Calochilus paludosa

Australia has many pseudocopulatoryorchids!

OphrysEurope

Tolumnia henekeniiHispaniola

Cyrtidiorchis sp.

South America

Chrysocycnis schlimmii

Mormolyca ringens Mormolyca schweinfurthiana

Trigonidiumgrande

Telipogon sp.

Sexual deceit—

Pollination by maleTachinid flies

Telipogon sp.

Telipogon sp.

Trichoceros antennifer

PseudocopulatoryPseudocopulatory pollination of pollination of LepanthesLepanthes gleicensteiniigleicensteinii

Mario Blanco & Gabriel Barbosa, Ann. Bot. 95:763-772.

720+ spp.

Food or Brood site deceptionFood or Brood site deception

Not well studied, but probably not rareNot well studied, but probably not rarePossible examples:Possible examples:DraculaDracula ---- pollinated by pollinated by DrosophilidDrosophilidflies; mimicry of yeast?flies; mimicry of yeast?PaphiopediumPaphiopedium ---- some pollinated by some pollinated by syrphidsyrphid flies; mimicry of aphids (prey for flies; mimicry of aphids (prey for larvae)?larvae)?

Paphiopedilumglanduliferum

Dracula sp.

Dracula chestertonii

Lip mimics mushroom--visual, chemical mimicry?

Lip of Dracula sp. atFinca Dracula, Panama

Fly pollination in Fly pollination in PaleotropicalPaleotropicalBulbophyllumBulbophyllum and and CirrhopetalumCirrhopetalum

““Motel 6Motel 6”” syndromesyndrome

Bees seek out flowers to sleep in Bees seek out flowers to sleep in overnightovernightNo obvious food rewardNo obvious food rewardChemical attractants?Chemical attractants?Confirmed only for European genus Confirmed only for European genus SerapiasSerapias

Serapiaslingua

Trap mechanismsTrap mechanisms

Found in association with various Found in association with various reward/attractant syndromesreward/attractant syndromesPollinators are lured into an area they Pollinators are lured into an area they cancan’’t escape, then forced to exit past t escape, then forced to exit past the columnthe columnOr, the pollinator may be forcibly thrown Or, the pollinator may be forcibly thrown against the columnagainst the column

Selenipedium antioquiense

Porroglossum eduardii

Lip open

Lip closed

Active trap mechanisms

Some pleurothallid flowershave sensitive, motile lips(similar to Venus Fly Trap)

Insect landing on lip triggers lip to close, liftinginsect into contact withcolumn.

Coryanthes sp.

Fragrance attractant;Liquid-filledbucket trap

CoryanthesCross-section

Nectar DeceitNectar Deceit

Relatively few orchids actually produce Relatively few orchids actually produce a nectar reward (energetically a nectar reward (energetically expensive? Longexpensive? Long--distance pollen distance pollen movement?)movement?)Most have empty Most have empty nectariesnectaries; deceive ; deceive pollinatorspollinatorsMight be mimics of other nectarMight be mimics of other nectar--producing nonproducing non--orchids in same habitatorchids in same habitat

Cochleanthes anatona

Sepaline false nectary

Oil deceitOil deceit

Many species of Many species of OncidiumOncidium do not offer do not offer an oil reward, but are thought to mimic an oil reward, but are thought to mimic flowers of the nonflowers of the non--orchidaceous orchidaceous MalpighiaMalpighia (an oil(an oil--reward reward eudicoteudicot) or ) or CalceolariaCalceolaria..Typical yellow/brown Typical yellow/brown ““oncidioidoncidioid”” flowers flowers occur in many unrelated occur in many unrelated cladesclades of of subtribesubtribe OncidiinaeOncidiinaeTaxonomic confusion!Taxonomic confusion!

Malpighia spp.--- Oil reward flowerModel for many yellow “Oncidiums”?

OTHER MODELS ???CALCEOLARIA & OTOGLOSSUM HARLINGII

Calceolaria is an oil reward flower; sympatric with “Oncidiums” at higher elevations in the Andes

Chelyorchisampliata

Tolumniaurophylla

Tolumniaguianensis

Orchids that are good at fooling pollinators are also goodat fooling orchid taxonomists!

Rhizanthella gardneriTermite pollination

PlatantheraPlatanthera: Using Molecular Phylogenetics to : Using Molecular Phylogenetics to Study Adaptation to Different PollinatorsStudy Adaptation to Different Pollinators

Work of Work of HapemanHapeman and Inoue (1997)and Inoue (1997)Used DNA sequencing to produce a Used DNA sequencing to produce a phylogenetic tree; used phylogenetic tree; used characters characters independent of floral traitsindependent of floral traitsThen, mapped floral characters onto Then, mapped floral characters onto tree, allowing evolution of traits to be tree, allowing evolution of traits to be tracedtraced

Floral Diversity in Platanthera

PlatantheraPlatanthera: Take: Take--home messageshome messages

PollinationPollination--related floral traits (color, related floral traits (color, size, spur length, etc.) undergo rapid size, spur length, etc.) undergo rapid and frequent evolutionary changeand frequent evolutionary changeFloral traits are Floral traits are ““homoplasioushomoplasious””=evolutionarily labile=evolutionarily labileOrchid classifications should Orchid classifications should NOTNOT be be based primarily on floral characters!based primarily on floral characters!

Emphasis on gross floral characters can result in incorrect classifications!

Dendrophylax fawcetti

“Campylocentrum” filiformis

Dendrophylax filiformis

CoevolutionCoevolution??

Orchids are highly adapted to utilize Orchids are highly adapted to utilize specific pollinators, butspecific pollinators, but……..Do orchids affect the evolution of their Do orchids affect the evolution of their animal pollinators?animal pollinators?““Orchid and bee marching petal in Orchid and bee marching petal in tarsus down the aisle of tarsus down the aisle of coevolutioncoevolution””??

CoevolutionCoevolution??

NoNo---- no evidence that orchids affect the no evidence that orchids affect the evolution of morphology or behavior of evolution of morphology or behavior of their pollinatorstheir pollinatorsMost orchids are rareMost orchids are rare----not the primary not the primary source of nectar or other rewards for source of nectar or other rewards for their pollinatorstheir pollinatorsProbably Probably ““parasitesparasites”” on other on other plant/pollinator systemsplant/pollinator systems

Is Pollinator Specificity Is Pollinator Specificity OverOver--estimated?estimated?

How many observations are needed to How many observations are needed to document pollinator set for an orchid?document pollinator set for an orchid?What about seasonal, geographic What about seasonal, geographic variation?variation?For most species, we donFor most species, we don’’t have t have enough observations to adequately enough observations to adequately measure pollinator specificitymeasure pollinator specificity

How many species?

How manypolllinators,fungal partners?Conservation—Ex situ, in situ?

What can you do to conserve What can you do to conserve orchids?orchids?

$45 buys 1 acre of montanerainforest– makes a greatbirthday or holiday gift

Ecominga Foundation: purchasing land toconserve Ecuador’s orchid-rich habitats:www.loujost.com

AcknowledgementsAcknowledgements

National Science FoundationNational Science FoundationAmerican Orchid SocietyAmerican Orchid SocietyMarie Selby Botanical GardenMarie Selby Botanical GardenAtlanta Botanical GardenAtlanta Botanical GardenMany commercial & private growersMany commercial & private growers