Transcript Plant Phylogeny Notes

Today’s Plan: 3/30/10
 Bellwork: Mass plants and record
data (15 mins)
 Plant Phylogeny Begin Mosses (45
mins)
 Plant Notes (25 mins)
Today’s Plan: 3/31/2010
 Bellwork: Mass Plants and record data
(15 mins)
 Moss/Fern Lab (45 mins)
 Notes continued (25 mins)
Today’s Plan: 4/6/10
 Bellwork: Discuss last week/due
dates(5 mins)
 Leaf, Stem, and Root lab (50 mins)
 Finish plant phylogeny notes, begin
Plant structure and function notes (25
mins)
Plant evolution and phylogeny
 Plants are belived to have evolved from
green algae about 500 million years ago
 There are 4 main things that plants and
algae have in common:
 Rosette-shaped cellulose-synthesizing
complexes
 Peroxisome enzymes (that minimize loss of
organic products of photorespiration)
 Flagellated sperm (in some plant species)
 Phragmoplast (microtubule structure that forms
between the daughter nuclei, which allows the
cell plate to form between the two new cells
Moving to land
 Why move to land?
 No water to filter out sunlight
 Abundance of space with minimal competition
 More abundant CO2 in air than in water
 In order to colonize land, plants required
the following adaptations:
 A root system for absorbing water and
anchoring
 Structural adaptations to allow the organism to
be upright
 Structural adaptations to prevent the organism
from drying out
How’d they do it?
 Before the evolution of roots, plants used
mycorrhizal relationships for absorption of
water and nutrients from the soil
 Plants evolved a waxy cuticle
 Plants produced secondary compounds (not
primary products of plant metabolism) that
produce strong tastes and odors to deter
attack by pathogens and predators, and to
block harmful UV rays
Plant Derived Characters
 Alternation of Generations (doesn’t occur in
green algae, so it appears to have
convergently evolved)
 Haploid gametophyte, Diploid sporophyte
 Walled spores produced in sporangia
 Multicellular gametangia
 Structures that produce gametes
 Apical Meristems
 Regions of growth where the plant elongates at
the ends of the stem
Figure 30-15
Egg (n)
Gametes are produced
in gametangia
Haploid (n)
Diploid (2n)
Sperm (n)
Zygote (2n)
(retained on
parent)
Multicellular
adult (n)
Spores (n)
Figure 30-16
Haploid (n)
Diploid (2n)
Gametes (n)
Gametophyte
(n; multicellular,
haploid)
Zygote
(2n)
Sporophyte
(2n; multicellular,
diploid)
Spores (n)
Figure 30-13
Antheridium
Sperm form in antheridia.
Eggs form in archegonia.
Egg
Plant Phylogeny
 Of course, there’s much debate about the
degree to which plants are related to one
another, but based on certain
characteristics, we group plants into 3 main
categories:
 Nonvascular plants (Bryophytes)
 Seedless Vascular Plants (Ferns and Fern allies)
 Seed Plants (two sub-groups):
 Naked-seed plants (Gymnosperms)
 Flowering plants (Angiosperms)
Figure 30-9
Eukarya
Green plants
Land plants
Vascular plants
Seed plants
Gymnosperms
Flowers
Seeds
Vascular tissue
Green algae
Nonvascular plants
Seedless vascular plants
Ability to live on land
Chloroplasts containing chlorophyll a + b and -carotene
Angiosperms
Figure 30-7l
Nonvascular plants do not have vascular tissue to conduct water and provide support.
Hepaticophyta (liverworts) Anthocerophyta (hornworts)
Bryophyta (mosses)
Seedless vascular plants have vascular tissue but do not make seeds.
Lycophyta (lycophytes
or club mosses)
Psilotophyta
(whisk ferns)
Sphenophyta (horsetails)
Pteridophyta (ferns)
Figure 30-7c
Seed plants have vascular tissue and make seeds.
Cycadophyta (cycads)
Ginkgophyta (ginkgo)
Other conifers (redwoods,
junipers, yews)
Gnetophyta (gnetophytes) Pinophyta (pines, spruces, firs) Anthophyta (angiosperms
or flowering plants)
Some distinctions
 Vascular Tissue
 This is a series of tubes for carrying water and
nutrients up and down the plant. There are 2 types:
 Phloem-carries sugars from photosynthesizing parts to
the rest of the plant (mostly downward moving)
 Xylem-carries water and nutrients (mostly upward
moving)

Includes tube shaped cells called tracheids and contain
lignin
 Spores vs. Seeds
 Spores are haploid cells that will grow into
multicellular gametophytes
 Seeds are analogous to eggs of birds. They contain
the plant embryo, endosperm (nutirent tissue), and a
protective seed coat
Figure 30-11
First vascular tissue
Simple waterconducting cells
Tracheids
Vessel elements
Ends have gaps
in secondary
cell wall (inside)
Primary wall
(with cellulose)
Primary wall
(with cellulose)
Lignin
Little structural
support. Found in
fossils and presentday mosses
Ends have gaps
through primary and
secondary cell walls
Primary wall
(with cellulose)
Primary wall
(with cellulose)
Secondary wall
(with lignin)
Secondary wall
(with lignin)
Some structural
support. Found
in fossils
Increased structural
support. Found in
all vascular plants
Found in gnetophytes
and angiosperms
Figure 30-20a
Seeds package an embryo with a food supply.
Embryo
Nutritive tissue
Protective coat
Non-vascular plants (Bryophytes)


Consist of 3 phyla: Hepatophyta (liverworts), Anthocerophyta (hornworts)
and the Bryophyta (Bryophyta)
Gametophyte is the dominant portion of the life cycle




Spores need moist soil or tree bark to produce the protonema (filaments that
absorb water and minerals via osmosis), which produce “buds” with an apical
meristem that produces the gametophore
Gametophyte is anchored by rhizoids, which are long, tubular cells or filaments of
cells
When mature, the gametophyte forms the gametangia, which forms the gametes.
The antheridia produces a flagelated sperm which swims to the archegonium
which contains the egg
Sporophyte





Remains attached to the gametophyte, as it cannot survive on its own when
young.
The foot of the sporophyte stays embedded in the archegonium to absorb
nutrients
The seta(e) conducts the absorbed nutrients to the sporangium (which is also
called a capsule)
The sporangium produces the spores via meiosis. Peristomes appear as teeth on
the upper part of the capsule which can open under moist conditions to release
spores, and close under dry conditions
In the hornworts and mosses, the sporphytes have stomata which are the same in
function to those on the leaves of more complex plants
Figure 30-17a
Mosses: Gametophyte is large and long lived; sporophyte depends on gametophyte for nutrition.
Archegonium
Haploid (n)
Diploid (2n)
FERTILIZATION
Egg (n)
Eggs form in archegonia
Zygote
(2n)
Sperm
swim
to egg
Sperm form in antheridia
Developing
sporophyte
(2n)
Mature
sporophyte
(2n)
Developing
sporophyte
(2n)
Spores (n) are produced in
sporangia by meiosis,
dispersed by wind
Mature
gametophyte (n)
Developing
gametophyte
Mature
gametophyte (n)
Spore (n)
Figure 30-35
Moss in dry weather
Moss in wet weather
Figure 30-36
Marchantia bryophyta
Figure 30-37
Phaeocerus leavis
Figure 30-18
Hornwort gametophytes and sporophytes
Horsetail gametophytes and sporophytes
Figure 30-41
Equisetum arvense
The Ecological Importance of
Bryophytes
 Like lichens, can live in extreme environments b/c
they can survive losing most of their water, then
rehydrating, so they’re a good source of food for
organisms all over the planet
 One wetland moss, peat moss, forms extensive
deposits of decayed organic matter (peat), this is a
source of fuel in Europe and Asia, and is a good soil
conditioner for plants that are transported, as it
absorbs lots of water
 Peat acts as a carbon reservoir to help stabilize
atmospheric carbon concentration as well
 Peat also inhibits decay, so things that die in
peatlands are preserved for thousands of years
Seedless vascular plants




Ferns and Fern allies
Sporophyte is the dominant part of the life cycle-this is the leafy
plant that you’re used to seeing (the gametophyte is extremely
small)
Vascular Tissue-Allows the plant to get much taller than the
Bryophytes
Evolution of roots and leaves



Roots also contain lignified vascular tissue and serve to anchor as well
as absorb. Scientists think that they may have evolved from
underground portions of stems. It is believed that the evolution of
roots is the result of convergent evolution and not from a common
ancestor of all plants
Leaves are believed to be evolved from Microphylls, small spine-shaped
with 1 bundle of vascular tissue, into megaphylls, complex with
branched vascular tissue
Spore Variation-sporophylls first evolved in these plants (leaves
that have sporangia). These are sometimes called fertile fronds



Sporangia are called sori and are usually on the sporophyll
Most are homosporous (producing one type of sporangium and spore
with a bisexual gamete)
Seed plants are heterosporous, producing megaspores (develop into
female gametes), or microspores (develop into male gametes)
Figure 30-17b
Ferns: Sporophyte is large and long lived but, when young, depends on gametophyte for nutrition.
Spore
(n, dispersed
by wind)
Spores are
produced in
sporangia
Mature
gametophyte
(n, underside)
Developing
gametophyte
(n)
1 mm
Sporophyte
(2n; develops on
gametophyte) Archegonium
Mature
sporophyte (2n)
Gametophyte
(n; side view)
Sperm
swim
to egg
Zygote (2n)
Sperm develop
in antheridia
Eggs develop
in archegonia
Figure 30-42
Ferns range in size.
Gonocormus minutus
Dicksonia antarctica
Fern sporangia
Polypodium vulgare
Collection of
sporangia
Figure 30-19
Figure 30-10
Cuticle is a waxy layer that prevents
water loss from stems and leaves.
Cuticle
Leaf cross section
Moist
photosynthetic
cells
Stomata have pores that allow gas
exchange in photosynthetic tissues.
Pore
Guard cells
Stoma
Classification of Seedless Vascular
Plants
 2 Phyla:
 Lycophyta-club mosses, spike mosses, and Quill
worts
 This is the most ancient group of vascular
plants
 Despite the common names, they are not true
mosses
 Pterophyta-ferns, horsetails, Whisk ferns
 These are most closely related to the seed
plants and are the most widespread group of
seedless vasculars
 Many whisk ferns are “living fossils” b/c they
closely resemble fosslized plants
Figure 30-39
Lycopodium species
Figure 30-40
Tmesipteris species
The Importance of Seedless
Vascular Plants
 The evolution of these plants meant
the acceleration of photosynthesis,
which prompted a rapid drop in
carbon dioxide levels in the
atmosphere (by as much as a factor
of 5)
 These plants formed the first forests,
which became peat and eventually
coal
Figure 30-4
Plant-based fuels
COAL FORMATION
1. Dead plant material
Wood
Coal
accumulates in marshy
or boggy habitats.
Petroleum and
natural gas
What energy
sources do you
think will be
important in
the future?
2. If oxygen in water is
scarce, the organic
matter decays only
partially, forming peat.
Peat
Pressure
Pressure
Sediments
Coal
3. If the peat deposits
are later covered by
sediments and
compressed, the
resulting pressure and
heat change them
into coal.
Seed Plants

Like the seedless vasculars, Sporophyte is dominant , and
gametophyte is microscopic




This has the advantage of protecting the delicate eggs
produced by the gametophyte from environmental stresses as
it’s retained within the parent sporophyte
Integument protects the megasporangium within the parent
plant. Ovule is formed by the megasporangium,
megaspore, and integument
Pollen is the microspore of the plant which consists of the
male gametophyte enclosed in the pollen wall
Seeds are considered an evolutionary advantage because it
contains endosperm and protects the embryo from
dessicating (the seed coat is thicker than the wall of a
spore), and seeds can be dispersed in a number of ways


Animals
Wind, water
Gymnosperms
 These are the first of the seed plants, but produce
what’s called a “naked” seed, since the seed is not
encased in a fruit
 Seeds are typically produced within cones
 Include the following Phyla
 Cycadophyta (cycads)-2nd largest group of
gymnosperms, with about 130 surviving species
today, but were the dominant plant during the age of
dinosaurs
 Ginkophyta (ginkos)fan-like leaves, and originally
thought to be extinct. Only male trees are planted
b/c the seeds produced by the female smell rancid
 Gnetophyta-tropical plants in 3 genera
 Coniferophyta (pines, sequoia, juniper, firs)-largest
and most diverse group of gymnosperms
Figure 30-21
Pollen grains
disperse via wind
Cones with
microsporangia
Microspore (n)
forms pollen
grain
Pollen grain
(male gametophyte
Megasporangium
Four meiotic
products; one is
large and forms
the megaspore (n)
Three meiotic
products die
Ovulate cone
Pollen
grain
Ovules (contain
megasporangia)
Female
gametophyte (n)
Mother
cell (2n)
Archegonia
Embryo
(2n)
Eggs (n)
Mature
sporophyte (2n)
Developing
sporophyte
Seed (disperses
via wind or animals)
Pollen produces
sperm
Megaspore divides to form
female gametophyte (n), which
produces archegonia and eggs
by mitosis. (Only one egg is
fertilized and develops.) Note
that the red dots here and
elsewhere represent nuclei
Figure 30-44
Cycas revoluta
Figure 30-45
Fossil ginkgo
Ginkgo huttoni
Living ginkgo
Ginkgo biloba
Figure 30-47
Cones that produce
macrosporangia and pollen
Picea abies
Pollen
Cones that produce
macrosporangia and eggs
Picea abies
Figure 30-48
Thuja plicata
Angiosperms
 These are the flowering plants and produce fruits that
house the seeds
 These are advantageous b/c of the greater variety of
ways that animals can help with pollination and
dispersal
 The fruit contains more endosperm and is the mature
ovary of the plant
 Flowers have adaptations that ensure pollination, like
nectar, scent, color, and shape
 2 main types:
 Monocotyledons
 Dicotyledons
MONOCOTS
Figure 30-27
Cotyledon
Parallel veins in leaves
(bundles of vascular tissue)
Flower petals in
multiples of 3
Branching veins in leaves
Flower petals in
multiples of 4 or 5
DICOTS
One cotyledon (inside seed) Vascular tissue scattered
throughout stem
Two cotyledons
Vascular tissue in circular
arrangement in stem
Figure 30-22
Pollen grains disperse via wind
or animals (the red dots here Pollen lands
and elsewhere are nuclei)
near female
MITOSIS
gametophyte;
produces
pollen tube
Microspore (n)
Pollen grain
and sperm
forms pollen grain (male gametophyte)
Anther
Sperm travel
down growing
pollen tube to
reach egg
Stamen
Carpel
Flower
Ovule
MITOSIS
Ovary
Megasporangium
Mature
sporophyte
flower (2n)
Megaspore
(n: retained
in ovary)
Nutritive tissue
Female gametophyte
(n: retained in ovary)
Endosperm (3n)
forms nutritive
tissue in seed
Embryo (2n)
Zygote
(2n)
Developing
sporophyte
Seed (disperses
via wind or animals)
Egg
Figure 30-49
Animal-pollinated flower (this species produces both pollen
and eggs in the same flower)
Ornithogalum dubium
Wind-pollinated flower (this species has separate male and
female flowers)
Acer negundo
Male
flower
Acer negundo
Female
flower
Figure 30-23
Carrion flowers smell like rotting flesh and attract carrion flies.
Hummingbird-pollinated flowers are red and have long
tubes with nectar at the base.
Bumble-bee-pollinated flowers are often bright purple.
Figure 30-25
Fruits are derived from ovaries and contain seeds.
Seed
Wall of
ovary
Many fruits are dispersed by animals.
The Importance of plants
Carbon-fixation (photosynthesis)
Plants are the basis of food chains
Many plants are used medicinally
Many plants were selectively bred by
humans for food
 80% of all calories consumed by
humans comes from 6 crops: wheat,
rice, maize, potatoes, casava, and
sweet potatoes




Figure 30-2
Tertiary
Consumers:
Secondary
carnivores eat
carnivores.
Secondary
Consumers:
Carnivores
eat animals.
Primary
Consumers:
Herbivores
eat plants.
Producers:
Plants form
the base of
the terrestrial
food chain.
Figure 30-4-Table 30-1
Figure 30-3
Plants were domesticated at an array of locations.
Maize
Wild
ARTIFICIAL SELECTION CHANGES THE TRAITS OF
DOMESTICATED SPECIES.
Less
oil rich
Domestic
Oil rich
1. Observe variation
in kernel oil content.
2. Plant oil-rich
seeds and grow
to maturity.
North
America
Sunflower
3. Harvest kernels
South
America
from mature plants.
Repeat steps 1–3.
Potato
4. After many
generations, kernel
oil content increases.