Title: Chapter 30 Plant Diversity II Chapter 30: Plant Diversity II
1Chapter 30Plant Diversity II
2Chapter 30 Plant Diversity II
Fig. 29-7
Origin of land plants (about 475 mya)
1
Origin of vascular plants (about 420 mya)
2
3
Origin of extant seed plants (about 305 mya)
Liverworts
Nonvascular plants (bryophytes)
Land plants
Hornworts
1
ANCES- TRAL GREEN ALGA
Mosses
Lycophytes (club mosses, spike mosses, quillworts)
Seedless vascular plants
Vascular plants
2
Pterophytes (ferns, horsetails, whisk ferns)
Gymnosperms
3
Seed plants
Angiosperms
500
450
400
50
0
350
300
Millions of years ago (mya)
3What are five crucial adaptations that led the
success of seed Plants?
- Seeds
- Reduced gametophytes
- Heterospory
- Ovules
- Pollen
4Seeds
- Seeds changed the course of plant evolution,
enabling their bearers to become the dominant
producers in most terrestrial ecosystems - A seed consists of an embryo and nutrients
surrounded by a protective coat
5Reduced Gametophyte protection of antheridia and
archegonia
Fig. 30-2
PLANT GROUP
Mosses and othernonvascular plants
Ferns and other seedlessvascular plants
Seed plants (gymnosperms and angiosperms)
Reduced, independent(photosynthetic
andfree-living)
Reduced (usually microscopic), dependent on
surroundingsporophyte tissue for nutrition
Gametophyte
Dominant
Reduced, dependent ongametophyte for nutrition
Sporophyte
Dominant
Dominant
Gymnosperm
Angiosperm
Sporophyte(2n)
Microscopic femalegametophytes (n)
insideovulate cone
Microscopic femalegametophytes (n)
insidethese partsof flowers
Sporophyte(2n)
Gametophyte(n)
Example
Microscopic malegametophytes (n) insidethese
partsof flowers
Microscopic malegametophytes (n) inside
pollencone
Sporophyte (2n)
Sporophyte (2n)
Gametophyte(n)
6Heterospory The Rule Among Seed Plants
- The ancestors of seed plants were likely
homosporous, while seed plants are heterosporous - Megasporangia produce megaspores that give rise
to female gametophytes - Microsporangia produce microspores that give rise
to male gametophytes
7Ovules and Production of Eggs
- An ovule consists of a megasporangium, megaspore,
and one or more protective integuments
Immaturefemale cone
Integument
Spore wall
Megasporangium(2n)
Megaspore (n)
(a) Unfertilized ovule
8Pollen and Production of Sperm
- Microspores develop into pollen grains, which
contain the male gametophytes - Pollination
- Pollen eliminates the need for a film of water
and can be dispersed great distances by air or
animals - If a pollen grain germinates, it gives rise to a
pollen tube that discharges two sperm into the
female gametophyte within the ovule
Seed coat(derived fromintegument)
Integument
Femalegametophyte (n)
Spore wall
Egg nucleus (n)
Immaturefemale cone
Food supply(femalegametophytetissue) (n)
Male gametophyte(within a germinatedpollen
grain) (n)
Megasporangium(2n)
Dischargedsperm nucleus (n)
Embryo (2n)(new sporophyte)
Micropyle
Pollen grain (n)
Megaspore (n)
(c) Gymnosperm seed
(b) Fertilized ovule
(a) Unfertilized ovule
9The Evolutionary Advantage of Seeds
- A seed develops from the whole ovule
- A seed is a sporophyte embryo, along with its
food supply, packaged in a protective coat - Seeds provide some evolutionary advantages over
spores - They may remain dormant for days to years, until
conditions are favorable for germination - They may be transported long distances by wind or
animals
10Gymnosperms
Fig. 30-UN1
Nonvascular plants (bryophytes) Seedless vascular
plants Gymnosperms Angiosperms
- What are the four phyla of gymnosperms?
- Which phyla is the most biologically significant?
11Concept 30.2 Gymnosperms bear naked seeds,
typically on cones
- The gymnosperms have naked seeds not enclosed
by ovaries and consist of four phyla - Cycadophyta (cycads)
- Gingkophyta (one living species Ginkgo biloba)
- Gnetophyta (three genera Gnetum, Ephedra,
Welwitschia) - Coniferophyta (conifers, such as pine, fir, and
redwood)
12Phylum Cycadophyta
- Individuals have large cones and palmlike leaves
- These thrived during the Mesozoic, but relatively
few species exist today
13Fig. 30-5a
Cycas revoluta
14Phylum Ginkgophyta
- This phylum consists of a single living species,
Ginkgo biloba - It has a high tolerance to air pollution and is a
popular ornamental tree
15Fig. 30-5b
Ginkgo bilobapollen-producing tree
16Fig. 30-5c
Ginkgo bilobaleaves and fleshy seeds
17Phylum Gnetophyta
- This phylum comprises three genera
- Species vary in appearance, and some are tropical
whereas others live in deserts
18Fig. 30-5e
Ephedra
19Fig. 30-5f
Welwitschia
20Fig. 30-5g
Ovulate cones
Welwitschia
21Phylum Coniferophyta
- This phylum is by far the largest of the
gymnosperm phyla - Most conifers are evergreens and can carry out
photosynthesis year round
22Fig. 30-5i
European larch
23Fig. 30-5j
Bristlecone pine
24Fig. 30-5k
Sequoia
25Fig. 30-5m
Common juniper
26The Life Cycle of a Pine A Closer Look
- Three key features of the gymnosperm life cycle
are - Dominance of the sporophyte generation
- Development of seeds from fertilized ovules
- The transfer of sperm to ovules by pollen
- The life cycle of a pine provides an example
Animation Pine Life Cycle
27Fig. 30-6-4
Key
Haploid (n)
Ovule
Diploid (2n)
Ovulatecone
Megasporocyte (2n)
Integument
Pollencone
Microsporocytes(2n)
Megasporangium(2n)
Maturesporophyte(2n)
Pollengrain
Pollengrains (n)
MEIOSIS
MEIOSIS
Microsporangia
Microsporangium (2n)
Survivingmegaspore (n)
Seedling
Archegonium
Femalegametophyte
Seeds
Foodreserves(n)
Spermnucleus (n)
Seed coat(2n)
Pollentube
Embryo(2n)
FERTILIZATION
Egg nucleus (n)
28Angiosperms
Nonvascular plants (bryophytes) Seedless vascular
plants Gymnosperms Angiosperms
- Angiosperms are seed plants with reproductive
structures called flowers and fruits - They are the most widespread and diverse of all
plants
29Fig. 30-7
Stigma
Carpel
Stamen
Anther
Style
Filament
Ovary
Petal
Sepal
Ovule
Video Flower Blooming (time lapse)
30Fruits
- A fruit typically consists of a mature ovary but
can also include other flower parts - Fruits protect seeds and aid in their dispersal
- Mature fruits can be either fleshy or dry
Animation Fruit Development
31Fig. 30-8
Tomato
Ruby grapefruit
Nectarine
Hazelnut
Milkweed
32Fig. 30-9
Wings
Seeds within berries
Barbs
33The Angiosperm Life Cycle
- The flower of the sporophyte is composed of both
male and female structures - Male gametophytes are contained within pollen
grains produced by the microsporangia of anthers - The female gametophyte, or embryo sac, develops
within an ovule contained within an ovary at the
base of a stigma - Most flowers have mechanisms to ensure
cross-pollination between flowers from different
plants of the same species
34- A pollen grain that has landed on a stigma
germinates and the pollen tube of the male
gametophyte grows down to the ovary - The ovule is entered by a pore called the
micropyle - Double fertilization occurs when the pollen tube
discharges two sperm into the female gametophyte
within an ovule
35- One sperm fertilizes the egg, while the other
combines with two nuclei in the central cell of
the female gametophyte and initiates development
of food-storing endosperm - The endosperm nourishes the developing embryo
- Within a seed, the embryo consists of a root and
two seed leaves called cotyledons
36Fig. 30-10-4
Key
Haploid (n)
Diploid (2n)
Microsporangium
Anther
Microsporocytes (2n)
Mature flower onsporophyte plant(2n)
MEIOSIS
Generative cell
Microspore(n)
Ovule (2n)
Tube cell
Male gametophyte(in pollen grain)(n)
Ovary
Pollengrains
MEIOSIS
Germinatingseed
Stigma
Megasporangium(2n)
Pollentube
Embryo (2n)Endosperm (3n)Seed coat (2n)
Sperm
Seed
Megaspore(n)
Style
Antipodal cellsCentral cellSynergidsEgg (n)
Female gametophyte(embryo sac)
Pollentube
Sperm(n)
Nucleus ofdevelopingendosperm(3n)
FERTILIZATION
Zygote (2n)
Eggnucleus (n)
Discharged sperm nuclei (n)
37Animation Plant Fertilization
Animation Seed Development
Video Flowering Plant Life Cycle (time lapse)
38Fig. 30-13n
MonocotCharacteristics
EudicotCharacteristics
Embryos
One cotyledon
Two cotyledons
Leafvenation
Veins usuallyparallel
Veins usuallynetlike
Stems
Vascular tissueusually arrangedin ring
Vascular tissuescattered
39Fig. 30-13o
MonocotCharacteristics
EudicotCharacteristics
Roots
Taproot (main root)usually present
Root systemusually fibrous(no main root)
Pollen
Pollen grain withone opening
Pollen grain withthree openings
Flowers
Floral organsusually inmultiples of three
Floral organs usuallyin multiples of four or
five
40Basal Angiosperms
- Three small lineages constitute the basal
angiosperms - These include Amborella trichopoda, water lilies,
and star anise
41Fig. 30-13b
Water lily
42Fig. 30-13c
Star anise
43Magnoliids
- Magnoliids include magnolias, laurels, and black
pepper plants - Magnoliids are more closely related to monocots
and eudicots than basal angiosperms
44Fig. 30-13d
Southern magnolia
45Monocots
- More than one-quarter of angiosperm species are
monocots
46Fig. 30-13e
Orchid
47Fig. 30-13f
48Fig. 30-13g
Barley
Anther
Stigma
Ovary
Filament
49Eudicots
- More than two-thirds of angiosperm species are
eudicots
50Fig. 30-13h
California poppy
51Fig. 30-13j
Dog rose
52Fig. 30-13l
Zucchini flowers