The Great War ProjectThe Great War Project

The Biology of the The Biology of the FlowerFlower

It’s All About Sex!It’s All About Sex!

Perfect FlowersHave both male and female parts

Note: ‘carpel’ in diagram may also be called the pistil

Monocot vs. DicotMonocot vs. Dicot

Flowering plants (Angiosperms) fall into two Flowering plants (Angiosperms) fall into two broad plant groups; the monocots and the broad plant groups; the monocots and the dicotsdicots

Distinguishing the two groups is quite easyDistinguishing the two groups is quite easy Look at leaf veins; if veins are branching with a Look at leaf veins; if veins are branching with a

netted pattern the plant is a dicot; if leaf veins netted pattern the plant is a dicot; if leaf veins are parallel, then the plant is a monocotare parallel, then the plant is a monocot

Seeds of dicots can be split (eg. beans) while Seeds of dicots can be split (eg. beans) while seeds of monocots cannot be split (eg. corn)seeds of monocots cannot be split (eg. corn)

Flower DifferencesFlower Differences

Monocots have flower parts in multiples Monocots have flower parts in multiples of 3 while dicots have flower parts in of 3 while dicots have flower parts in multiples of 4 or 5 (note: petals may be multiples of 4 or 5 (note: petals may be fused in some flowers)fused in some flowers)

Many monocots have sepals that look Many monocots have sepals that look like petals giving the flowers the like petals giving the flowers the appearance that they have 6 petals. appearance that they have 6 petals. When petals and sepals look the same, When petals and sepals look the same, they are called tepals.they are called tepals.

Dicot flowersDicot flowers

Monocot flowersMonocot flowers

Imperfect Flowers: Imperfect Flowers: Monecious vs. DioeciousMonecious vs. Dioecious

While most flowers are both male and female, While most flowers are both male and female, some plants have separate male and female some plants have separate male and female flowersflowers

Mono = one ( monoecious plants have Mono = one ( monoecious plants have separate male and female flowers on the same separate male and female flowers on the same plant)plant)

Dio = two (dioecious plants have separate Dio = two (dioecious plants have separate male and female flowers on separate plants)male and female flowers on separate plants)

MonoeciousMonoecious

DioeciousDioecious

Flower colour importantFlower colour important

Certain colours attract certain pollinatorsCertain colours attract certain pollinators Moth pollinated flowers are generally Moth pollinated flowers are generally

white or highly fragrant, esp. at nightwhite or highly fragrant, esp. at night Bee flowers often pink, purple and blueBee flowers often pink, purple and blue Butterfly flowers often yellow, orange, redButterfly flowers often yellow, orange, red Bird-pollinated flowers often red, tubular Bird-pollinated flowers often red, tubular

with no fragrancewith no fragrance

Human vs. Insect VisionHuman vs. Insect Vision

Flower ShapeFlower Shape

Flowers fall into two broad shape Flowers fall into two broad shape categoriescategories

Radial Symmetry (Actinomorphic)Radial Symmetry (Actinomorphic) Bilateral Symmetry (Zygomorphic)Bilateral Symmetry (Zygomorphic)

A Special Case: DaisiesA Special Case: Daisies

A ‘single’ daisy is actually a tight cluster A ‘single’ daisy is actually a tight cluster of numerous, tiny, individual flowersof numerous, tiny, individual flowers

Collectively, they are referred to as a Collectively, they are referred to as a ‘head’ of flowers‘head’ of flowers

Outer flowers have a single, large Outer flowers have a single, large modified petal (called ray flower)modified petal (called ray flower)

Inner flowers are called disc flowersInner flowers are called disc flowers

What is the purpose of What is the purpose of this variability in flowers?this variability in flowers?

Ultimately, results in pollinationUltimately, results in pollination Mode of Pollination – Animal vs. WindMode of Pollination – Animal vs. Wind Many monoecious and dioecious plants Many monoecious and dioecious plants

are wind pollinatedare wind pollinated Actinomorphic (radial symmetry) flowers Actinomorphic (radial symmetry) flowers

most popular with flies/butterfliesmost popular with flies/butterflies Zygomorphic (bilateral symmetry) flowers Zygomorphic (bilateral symmetry) flowers

most popular with bees, hummingbirdsmost popular with bees, hummingbirds

Outbreeders vs. InbreedersOutbreeders vs. Inbreeders

Can often tell by looking at the flower whether it is an Can often tell by looking at the flower whether it is an inbreeder (self-pollinating) or outbreeder (cross-inbreeder (self-pollinating) or outbreeder (cross-pollinator)pollinator)

Inbreeder characteristicsInbreeder characteristics Few flowersFew flowers Small flowersSmall flowers No fragranceNo fragrance Mono-colouredMono-coloured No stripes (nectar-guides) on flowersNo stripes (nectar-guides) on flowers Anthers close to stigmaAnthers close to stigma Stigma not obviously visibleStigma not obviously visible

Outbreeders vs. InbreedersOutbreeders vs. Inbreeders

Outbreeder characteristicsOutbreeder characteristics Large number of flowersLarge number of flowers Large flowersLarge flowers FragrantFragrant Brightly colouredBrightly coloured Stripes (nectar-guides) presentStripes (nectar-guides) present Anthers spaced from stigmaAnthers spaced from stigma Stigma large and obviousStigma large and obvious

Advantages of cross-Advantages of cross-pollination pollination

Increases genetic variability Increases genetic variability Adaptation to changing conditionsAdaptation to changing conditions Strong evolutionary potential Strong evolutionary potential Successful colonization long-termSuccessful colonization long-term

BUT: depends on effective mode of cross-BUT: depends on effective mode of cross-pollinationpollination

Self-pollinationSelf-pollination

Advantage: reliable seed set regardless Advantage: reliable seed set regardless to pollinator activity and can allow a to pollinator activity and can allow a successful individual to rapidly colonize successful individual to rapidly colonize an area in the short-terman area in the short-term

Disadvantage: less genetic variability Disadvantage: less genetic variability thus cannot adapt to changing thus cannot adapt to changing environmentenvironment

Evolutionary dead-endEvolutionary dead-end

Orchids : the Ultimate Orchids : the Ultimate Flowering PlantFlowering Plant

Largest group of flowering plants – 20,000 Largest group of flowering plants – 20,000 speciesspecies

Considered the most highly-evolved flowerConsidered the most highly-evolved flower Little wastage of pollenLittle wastage of pollen Often use a specific group of pollinators, even Often use a specific group of pollinators, even

a specific species of pollinatora specific species of pollinator Orchid use mimicry more than any other group Orchid use mimicry more than any other group

of flowersof flowersPROBLEM: VERY sensitive to environmental PROBLEM: VERY sensitive to environmental

change and at risk for extinctionchange and at risk for extinction

1/3 of orchids use 1/3 of orchids use mimicrymimicry

Utilize pseudo-copulation Utilize pseudo-copulation May produce fragrance that mimics the May produce fragrance that mimics the

pheromones of a female insectpheromones of a female insect Part or all of the flower appears like the Part or all of the flower appears like the

female insectfemale insect Males try to mate with the flower, Males try to mate with the flower,

bringing about pollinationbringing about pollination

MUN Botanical GardenMUN Botanical Garden

For more information, please contact:For more information, please contact:

Todd Boland, Research HorticulturistTodd Boland, Research HorticulturistMUN Botanical GardenMUN Botanical GardenMemorial University of NewfoundlandMemorial University of NewfoundlandSt. John’s, NL, A1C 5S7St. John’s, NL, A1C 5S7Email: bgprograms@mun.caEmail: bgprograms@mun.ca