Today: What am I: Protistan Jeopardy! Plants, Part 1

Today:Today:

What am I: What am I: Protistan Protistan Jeopardy!Jeopardy!

Plants, Part 1Plants, Part 1

Defining the “Plants”Defining the “Plants”

Land plants form a monophyletic group Land plants form a monophyletic group of of embryophytesembryophytes that evolved from that evolved from

the green algaethe green algae

Within the “Plants”Within the “Plants”

Seven major Seven major clades of Land clades of Land

Plants have Plants have vascular tissue vascular tissue (tracheids), the (tracheids), the other three are other three are

nonvascularnonvascular

What Challenges Does Life What Challenges Does Life on Land Present?on Land Present?

Key Adaptations to Life on Key Adaptations to Life on LandLand

the the CuticleCuticle GametangiaGametangia to enclose and to enclose and

protect gametesprotect gametes EmbryosEmbryos (enclosed, (enclosed,

protected young plantsprotected young plants Pigments Pigments to protect from to protect from

UVUV Spore walls from Spore walls from

sporopolleninsporopollenin Mutualisitic associations Mutualisitic associations

with fungiwith fungi

Exploring Non-Vascular Exploring Non-Vascular PlanPlantsts

Liverworts, hornworts, Liverworts, hornworts, and mossesand mosses

Challenges to life Challenges to life without a vascular without a vascular system??system??

Check Check Out the Out the Moss Moss

Lifecycle!Lifecycle!

Cool Things Cool Things About About

MossesMosses

Other Seedless, Non-Vascular PlantsOther Seedless, Non-Vascular Plants

Liverworts:• probably most ancient• sporophyteas are shorter and often simpler• lots of asexual reproduction by fragmentation (gemmae cups for dispersal by raindrops!)


Hornworts differ in:• the Structure of the

chloroplast (plate-like)• having Stomata• potential for indeterminate growth of sporophytes (until

transport becomes limiting!)


Mosses:• far more abundant

today• utilize apical cell division • specialized cell type

(hydroid) provides water channels (but no lignin)

Exploring the Earliest Exploring the Earliest Vascular Plants (Seedless)Vascular Plants (Seedless)

Vascular Plant EvolutionVascular Plant Evolution

From their bryophyte-like From their bryophyte-like ancestors, inherit:ancestors, inherit:

Tissue-producing meristemsTissue-producing meristems GametangiaGametangia Embryos and the sporo-Embryos and the sporo-

phytes that develop from phytes that develop from themthem

StomataStomata CuticlesCuticles Sporopollenin-walled sporesSporopollenin-walled spores

Exploring the Earliest Vascular Exploring the Earliest Vascular Plants (Seedless)Plants (Seedless)

Vascular plants have Vascular plants have xylemxylem (water and (water and minerals; made minerals; made primarily of primarily of tracheidstracheids) and ) and phloemphloem (to transport (to transport sugars)sugars)

The Vascular Plants: Major The Vascular Plants: Major ChangesChanges

Have true vascular Have true vascular tissue (phloem and tissue (phloem and xylem)xylem)

Dominant sporophyte Dominant sporophyte generationgeneration

Branched sporophytesBranched sporophytes These early vascular These early vascular

plants are all seedlessplants are all seedless

A Fern LifecycleA Fern Lifecycle

What do you

remember about this lifecycle??

The GymnospermsThe Gymnosperms“Naked Seeds”“Naked Seeds”

What’s new and What’s new and exciting about exciting about

the the gymnosperms gymnosperms

(conifers)??(conifers)??

The GymnospermsThe Gymnosperms“Naked Seeds”“Naked Seeds”

3 Major Adaptations:3 Major Adaptations:

1.1. Continued Continued reduction of reduction of gametophytegametophyte

2.2. Evolution of the Evolution of the seedseed

3.3. Evolution of Evolution of pollenpollenArabidopsis thaliana pollen grains Microscopy by Juergen

Berger, computer image manipulation by Heiko Schoof

1. Reduction of the Gametophyte1. Reduction of the Gametophyte

2. Evolution of the Seed2. Evolution of the Seed

SEEDSEED = sporophyte embryo packaged with = sporophyte embryo packaged with a food supply in a protective coat.a food supply in a protective coat.

The fossilized remains of the Jeholornis prima, shown in an illustration, included about 50 well-preserved seeds in the bird's

stomach. (CNN.com)


All seed plants are heterosporous!

Megaspores (+ female gametophytes) retained within parent sporophyte!

OVULEOVULE(Integument + (Integument +

Megaporangium Megaporangium + Megaspore)+ Megaspore)

After fertilization, After fertilization, the ovule the ovule

develops into a develops into a SEEDSEED..


3. Evolution of Pollen3. Evolution of Pollen

MicrosporesMicrospores develop into develop into pollen grainspollen grains

Pollen grains mature to Pollen grains mature to become male gametophtyesbecome male gametophtyes

Transfer of pollen to ovule = Transfer of pollen to ovule = pollinationpollination

Doesn’t require water!!Doesn’t require water!!

GymnospermsGymnospermsOvules and seeds develop of the surface of Ovules and seeds develop of the surface of

specialized leaves called specialized leaves called sporophyllssporophylls

Gymnosperm EvolutionGymnosperm Evolution

Gymnosperm DiversityGymnosperm Diversity

Four extant Four extant phyla:phyla:

1.1. CycadsCycads

2.2. GinkgosGinkgos

3.3. GnetophytaGnetophyta

4.4. ConifersConifers•Few species of tropical, palm-like trees

•Symbiotic with N-fixing bacteria

•Toxic to livestock!


•One remaining species!

•Popular ornamental (pollution resistant)

•Produces Gingko and stinky, fleshy seeds

Four extant phyla:Four extant phyla:

1.1. CycadsCycads

2.2. GinkgosGinkgos


4.4. ConifersConifers


•3 very different genera:

Welwitschia, Gnetum, and Ephedra


1.1. CycadsCycads

2.2. GinkgosGinkgos



Government announces ban on ephedraWednesday, December 31, 2003 Posted: 7:58 AM EST (1258 GMT)

The debate over the safety of ephedra heated up after pitcher Steve Bechler died February

17.


•Largest group (pines firs, spruces, larches, yews, junipers, cedars, cypresses and redwoods)

•Mostly evergreen; dominant in N. hemisphere (where growing seasons are relatively short)


1.1. CycadsCycads

2.2. GinkgosGinkgos



Scale Scale from an from an Ovulate Ovulate Cone Cone

Thought Question For You…Thought Question For You…

Why to Conifers do so well here?

Shouldn’t they be outcompeted by the angiosperms

(flowering trees)??

Cool Cool Coniferous Coniferous

AdaptationsAdaptations

Minor Minor ModificationModification

ssBothBoth

gymnosperms gymnosperms and and

angiosperms angiosperms use use tracheidstracheids in their xylem.in their xylem.

Angiosperms also Angiosperms also use use vessel vessel

elementselements, and , and reinforce with reinforce with fiber cellsfiber cells!!

Major Major Modification: Modification: the Flower the Flower

4 circles of modified leaves:

1.Sepals (Calyx)

2.Petals (Corolla)

3.Stamens

4.Carpels

Hypothetical Origin of the CarpelHypothetical Origin of the Carpel

Describing FlowersDescribing FlowersFlowers may be Flowers may be completecomplete (have all (have all

four basic organs) or four basic organs) or incompleteincomplete (lacking one or more)(lacking one or more)

The Magnolia, a complete flower!

Photo: Daniel Mosquin

Plants may be Plants may be monoeciousmonoecious (one (one house) or house) or dioeciousdioecious (two houses) (two houses)

One Strategy…One Strategy…

Describing FlowersDescribing FlowersFlowers may be described as Flowers may be described as bilateralbilateral or or

radialradial..

Describing FlowersDescribing FlowersFlowers may be clustered together to Flowers may be clustered together to

form an form an inflorescenceinflorescence

Fruits are Mature OvariesFruits are Mature OvariesFruits protect seeds and aid in their Fruits protect seeds and aid in their

dispersaldispersal

Ovary wall becomes the Ovary wall becomes the pericarppericarp (thickened wall of the fruit(thickened wall of the fruit))

Fruits are Mature OvariesFruits are Mature Ovaries

Types of FruitTypes of Fruit1. 1. Simple Fruit-Simple Fruit- derived from a single ovary derived from a single ovary

2. 2. Aggregate Fruit-Aggregate Fruit- derived from a single flower derived from a single flower with several carpelswith several carpels

3.3. Multiple Fruit-Multiple Fruit- develops from a group of develops from a group of flowers tightly clustered together (inflorescence)flowers tightly clustered together (inflorescence)

4.4. Accessory FruitsAccessory Fruits – develop from additional – develop from additional partsparts

Angiosperm Evolution and Angiosperm Evolution and DiversityDiversity

The AngiospermsThe Angiosperms

Evolution of the Flower!Evolution of the Flower!

Traditional taxonomy = 2 ClassesTraditional taxonomy = 2 Classes

Monocots Monocots

and and

DicotsDicots

Jack-in-the-Pulpit, Arisaema triphyllum

Not Monophyleti

c!

Angiosperm LifecyclesAngiosperm Lifecycles

Like the Gymnosperms:Like the Gymnosperms: HeterosporousHeterosporous Flower of the sporophyte Flower of the sporophyte

produces microspores produces microspores (will form male (will form male gametophytes) and gametophytes) and megaspores (will form megaspores (will form female gametophytes)female gametophytes)

Angiosperm LifecyclesAngiosperm Lifecycles

In Angiosperms, In Angiosperms,

Each pollen grain has Each pollen grain has two haploid cells.two haploid cells.

Ovules develop within Ovules develop within the the ovaryovary, contain the , contain the female gametophyte or female gametophyte or embryo sac.embryo sac.

(Even further reduction of (Even further reduction of gametophyte generation!)gametophyte generation!)

Double

zygote

SPOROPHYTE (2n)

GAMETOPHYTE (n)

GREEN ALGA BRYOPHYTE FERN GYMNOSPERM ANGIOSPERM

Sporophyte Dominant: An Evolutionary Trend

Cross-PollinationCross-Pollination

Some flowers can self-Some flowers can self-pollinate, but most use pollinate, but most use diverse strategies to diverse strategies to ensure cross-pollinationensure cross-pollination

Angiosperms Shape Angiosperms Shape EvolutionEvolution

By the end of the By the end of the Cretaceous (65 mya) Cretaceous (65 mya) angiosperms are the angiosperms are the dominant plants on dominant plants on

Earth.Earth.

Plants and their Plants and their pollinators and pollinators and

dispersers are a good dispersers are a good example of example of

coevolutioncoevolution (mutual (mutual evolutionary influence)evolutionary influence)

Other Notes about Other Notes about AngiospermsAngiosperms

- - Ecologically importantEcologically important

- Major human food - Major human food sourcesource

- Source of unique - Source of unique secondary compounds secondary compounds (drugs!)(drugs!)

““Diversity is a non-Diversity is a non-renewable resource!”renewable resource!”

Documents

Today: What am I: Protistan Jeopardy! Plants, Part 1