Kingdom Plantae:Angiosperms

Flowering plants• 2 Classes: Monocots and dicots• Flower part # already

discussed.• Other differences:• 1) Cotyledons or seed leaves,

first leaflike structure of embryo in seed

• Monocots with 1• Dicots with 2.

2 cotyledons

1 cotyledon

Flowering plants• Other differences:• 2) Leaf venation:

– Dicots netted venation– Monocots parallel venation

Flowering plants• Other differences:• 3) Lateral meristems (secondary or lateral

growth), making woody stems– Dicots: some do– Monocots: most do not

Flowering plants• Summary table: monocots versus dicots

Flowering plants• Recap life cycle: pollination brings male gametophyte

to stigma of flower.

Pollination syndromes• Pollination syndrome is a set of flower features that

adapt them to a certain group of pollinating animals• Coevolution: when traits of one organism evolve in

response to traits of another• Here, we characterize floral and animal traits that

adapt flowers to particular types of animal pollinators

• Disclaimer: Note that we must make broad generalizations and exceptions exist to most of the following statements!

Pollination syndromes• Bee pollination• Bees are:

– intelligent– agile– visual animals: good eyesight (including UV light)– good smellers (good sense of smell) – strong (some)– active during day.

Pollination syndromes• Bee pollination• Bee pollinated flowers are:

– Colorful (usually not red)– Have landing platform: place where bee can land on flower

as bee does its business– Mildly fragrant.

Pollination syndromes• Bee pollination• Bee pollinated flowers:

– May have nectar guides: patterns of lines or dots that can guide bee to reward

– Sometimes these only visible in UV light (which bees see).

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

Orchid flowerwith nectarguides (lines)on petals

Pollination syndromes• Beetle pollination• Beetles are:

– Relatively clumsy– Have poor vision– Not very smart– Active during the day (many flower-visiting ones).

Pollination syndromes• Beetle pollination• Beetle pollinated flowers are:

– Relatively large or grouped into large inflorescences– Light colored– Smelly (fruity or spicy smell)

Inflorescence ofXanthosoma withbeetle from it

Dogwood inflorescence

Pollination syndromes• Bird pollination• Birds are:

– agile– long-beaked– visual: see red colors well– poor “smellers”: lack good

sense of smell

• Hummingbirds (native to Americas) can hover: don’t need to land to access flower rewards.

Pollination syndromes• Bird pollination• Bird-pollinated flowers are: red or orange (also

yellow), have nectar hidden by long floral tube, little or no fragrance, no landing platform.

Aloe Anisacanthus (Acanthaceae) flower

Pollination syndromes• Bird pollination: not always by hummingbirds• Other birds from other areas:• Sunbirds (Africa/Asia)• Honeycreepers (Hawai’i).

Golden-wingedsunbird

Iiwi (a honeycreeper)

Crested honeycreeper

Pollination syndromes• Butterfly pollination• Butterflies have: good vision, good sense of smell,

long coiled tongue. Must land on flower to visit it (can’t hover).

coiled tonguetongue extended

Pollination syndromes• Butterfly-pollinated flowers:

– Color varies (blue, yellow, orange)– Landing platform present– Nectar at bottom of floral tube

Phlox flowersPlumbago flowers

Pollination syndromes• Fly pollination• Flies have good sense of smell,

especially flesh flies• Attracted to rotting meat (lay eggs in

meat, larvae are maggots).

Pollination syndromes• Fly-pollinated flowers:

– Smell like rotting meat– Look like rotting meat (dark red,

purple)– Offer no reward: flies fooled by

flower.

Stapelia flower

Fly flower story: Rafflesia• Ex, Rafflesia

of Sumatra

• Root parasite

• Flower is only above-ground part.

Fly flower story: Rafflesia

• Ex, Rafflesia of Sumatra

• Largest single flower on Earth.

Pollination syndromes• Fly pollination• Largest inflorescence is made by fly-

pollinated plant• Corpse-flower.

Inside view

Pollination syndromes• Bat pollination• Bats are flying mammals

– Active at night (nocturnal)– Poor eyesight, good sense of smell– Agile, can hover when visiting flower.

QuickTime™ and aCinepak decompressorare needed to see this picture.

Pollination syndromes• Bat pollination• Bat-pollinated flowers

– Open at night– Produce lots of pollen and nectar as rewards– Are white or light-colored– Are very fragrant (sweet odor)– May be pendant (hang down from branches).

Parkia flowers

Pollination syndromes• Bat pollination: Mainly a tropical phenomenon• In U.S., saguaro cactus is one of few bat-pollinated

species.

Saguaro flowers

Saguaro cactus

Pollination syndromes• Moth pollination• Moths have:

– Poor vision (they are nocturnal)– Excellent sense of smell– Long coiled tongue.

Pollination syndromes• Moth pollination• Moths:

– Some (hawkmoths) can hover when visiting flowers.

Hawkmoth

Pollination syndromes• Moth pollination• Moth-pollinated flowers:

– Open at night– Produce lots of sweet fragrance– Are white or light-colored– Make nectar in tube.

Pollination syndromes• Interesting moth story: nectar spur• Nectar spur is long pouch, at bottom of which is

nectar• Moth uses long tongue to reach nectar• Only if tube is longer than tongue will moth have to

push into flower far enough to pick up pollen• So, long spurred flowers reproduce better.

Pollination syndromes• Which leads to longer moth tongues to reach all of the

nectar in the longer tubes• Which leads to longer tubes......• Some moth-pollinated orchids with long nectar spurs

(almost one foot long!)• Moth has extremely long tongue!

Pollination syndromes• Moth pollination• Angraecum orchid from Madagascar.

Nectar spur almost1 foot long!

Pollination syndromes• Sexual mimics• Flowers that mimic

female bees or wasps• Look/smell like

females• Males attempt to mate,

pick up pollen, then fly to another flower and repeat process

• No reward supplied!. Sexual mimicorchids

Pollination syndromes• Another trick flower• Grass pink orchid: grows in

pitcher plant bogs in SE US• Makes fake stamens on petal.

Calopogon orchid (flowermade upside down!)

Cattleya orchid (flowermade right side up)

Plant ecologyclass in bog

Value of Pollinators• Native pollinators

worth $20-40 billion/yr in U.S.

• 150 food crops rely on pollinators.

Value of Pollinators• Ex, blueberries in Alabama.

• Honeybees not efficient pollinators. Southeastern blueberry bee very efficient: each bee pollinates $75 worth of berries (visits 50,000 flowers/yr).

A SE blueberry bee on the job

Fruits• Recall that another unique feature of

angiosperms is fruit

• Fruit: Mature ovary of flower (contains one or more seeds)

• Exception is parthenocarpic fruits (fruits that do not contain seeds)

Fruits• Exception is parthenocarpic fruits (fruits that do not

contain seeds)

• How reproduce? Asexually. Commonly by rooting cuttings. Also tissue culture.

Fruits• Ovary wall becomes pericarp in fruit.

Fruits• Ovary wall becomes pericarp in fruit

• Pericarp may develop specialized layers. At most these are:– ectocarp: outer layer

– mesocarp: middle layer

– endocarp: inner layer

Fruits

• Major fruit types:• 1) Simple fruits: single

flower, one pistil• 2) Aggregate fruits:

single flower, many separate pistils

• 3) Multiple fruits: many fused ovaries of many flowers.

Fruits

• Another fruit term: accessory fruit• When tissues other than ovary form

part of fruit• Example: strawberry• Receptacle is red part• Each small structure on outside is 1

ovary from single small pistil.

receptacle

Individual small fruits

Fruits

• Pineapple flowers and fruit

Small, pink flowers visible.Each one contributes 1 ovary to fruit

Aggregate Fruits• Raspberry, strawberry as

aggregate fruits

Raspberry

Strawberry

Simple Fruits• Can be divided into fleshy and dry fruits

– Fleshy fruits:• Pome: accessory tissue (fused sepals, petals,

stamens=hypanthium) makes fleshy part.

Simple Fruits• Can be divided into fleshy and dry fruits

– Fleshy fruits:• Drupe: fleshy outer layer, stony endocarp• Ex, peaches, plums, cherries, black walnuts

Simple Fruits• Can be divided into fleshy and dry fruits

– Fleshy fruits:• Berry: pericarp fleshy throughout• Ex, Tomatoes, grapes.

Muscadine grapes

Tomato

Simple Fruits• Can be divided into fleshy and dry fruits

– Special types of berries:• Hesperidium: exocarp leathery, separates from

inner layers, fruit divided into sections

Orange

Simple Fruits• Can be divided into fleshy and dry fruits

– Special types of berries:• Pepo: exocarp not separating from inner layers,

fruit not divided into sections• Ex, cucumber, squash, pumpkin.

Simple Fruits• Can be divided into fleshy and dry fruits

– Dry fruits• Dehiscent: Ovary wall breaks apart at maturity• Indehiscent: Ovary wall remains around seed at

maturity

Simple Fruits• Dry dehiscent fruits

– follicle: 1 carpel, dehisces along 1 edge

Simple Fruits• Dry dehiscent fruits

– legume: 1 carpel, dehisces along 2 edges

Simple Fruits• Dry dehiscent fruits

– silicle/silique: 2 carpels, septum in center of ovary

Simple Fruits• Dry dehiscent fruits

– capsule: >1 fused carpels, no septum, splits to release seeds.

Poppy capsuleCotton “boll” is capsule

Simple Fruits• Dry indehiscent fruits

– samara: one or more wings (pericarp outgrowths) present

wafer ash samarasmaple samaras

Simple Fruits• Dry indehiscent fruits

– nut: one seed, seed not fused to pericarp

– Ex, acorn, chestnut.

Acorn in cup Acorns

Simple Fruits• Dry indehiscent fruits

– achene: one seed, fused to pericarp at one point

– Ex, dandelion, sunflower.

Simple Fruits• Dry indehiscent fruits

– grain (caryopsis): one seed, fused entirely to pericarp

– Ex, corn, rice, wheat.

rice

Fruit functions• 1) Fruit can be protective against:

– Seed predators

– Environmental conditions

Fruit functions• 2) Fruit can promote seed dormancy

– Hard endocarp can seal out water/oxygen

– Breaking layer called scarification

Fruit functions• 2) Fruit can promote seed dormancy

– Hard endocarp can seal out water/oxygen

– Breaking layer called scarification

– Fleshy fruits can contain germination inhibitors (prevent seed from germinating in fruit)

– Rotting or digestion by animal gut needed to remove inhibitors so seed will germinate

Fruit functions• 3) Fruit can aid seed dispersal

– Mechanical dispersal: throws or squirts seeds

– Example, fruit of touch-me-not

Fruit functions• 3) Fruit can aid seed dispersal

– Physical forces dispersal• Wind (dandelion)• Water (coconut)

Dispersing dandelion fruits (achenes)

Fruit functions• Fruit can aid seed dispersal

– World’s largest seed (inside covering of fruit)

– Double coconut palm

Fruit functions• Fruit can aid seed dispersal

– Biological dispersal• Outside body: hooks, barbs, glue

Fruits of sandspur (Cenchrus)

Fruit functions• Fruit can aid seed dispersal

– Devil’s claw (Proboscidea)

– Makes fruit with large hooked claws (elongated top of capsule).

Devil’s claw fruits)

Extinct ground sloth with fruits attached

Now?

Fruit functions• Fruit can aid seed dispersal

– Biological dispersal• Inside body: Fleshy fruits (soft, sweet fruits)

Seed coat functions• 1) Protect embryo (like pericarp)

• 2) Promote seed dormancy (like pericarp)

Seed coat functions• 3) Aid in seed dispersal

– Hairs on some wind-dispersed seeds

Hairs on milkweed seeds Cotton is hairs on cottonseeds

Seed coat functions• 3) Aid in seed dispersal

– Elaiosome on ant-dispersed seeds– Elaiosome: food body on outside of seed coat

– Ants collect seed, remove elaiosome, discard seed underground or aboveground.

Stylophorum seeds Fremontodendron seeds

Seed coat functions• 3) Aid in seed dispersal

– Ant dispersal: Common for Eastern forest spring flowering plants.

TrilliumTrout lily

Hepatica

Bloodroot

Viola