Chapters 29-30
Yanchen Li
Chapters 29-30: The Diversity of Plants
Chapter 29.1: The origin of land plants
 Charophyceans, type of green algae considered most closely related to plants
 Shares several morphological similarities:
o Rosette Cellulose-Synthesizing Complexes
 -Rose shaped protein complexes that synthesize cellulose microfibrils
o Peroxisome Enzymes
 -Peroxisome enzymes help with minimizing lost organic products in photorespiration
o Similar Structure of Flagellated Sperm
 -The sperm of land plants with flagellated sperm closely resemble those of
Charophyceans
o Formation of a Phragmoplast
 -A structure made of Golgi derived vesicles and cytoskeletal elements found during the
mitosis of plant and Charophycean cells
 Genetic comparisons with nuclear and chloroplast genes also points towards a close relation between
Charophyceans and plants
 The development of traits like Sporopollenin (The tough material that surrounds spores) allow
Charophyceans to live through occasional drying, helped plant ancestors to move unto the land
Chapter 29.2: The Derived traits of land plants
 Plants possess 5 derived traits
o Apical Meristems
 Localized regions of cell division, allow the plant to reach new sources of minerals/
water
o Alternation of Generations
 Plants possess a lifecycle that alternates between a haploid (Gametophyte) and diploid
(Sporophyte) stage
o Walls Spores produced in Sporangia
 Sporophytes possess spore producing organs called Sporangia, the spores are protected
by a tough coat of Sporopollenin
o Multicellular Gametangia
 Organs in Gametophytes that produce gametes
 Female gametangia are Archegonia
 Male gametangia are Antheridia
o Multicellular, Dependent Embryos
 Plant embryos develop from zygotes and are fed by the parent plant through Placental
transfer cells
 Plants originated 475 mya (million years ago) diversified into several major groups
o Non-Vascular Plants: Bryophytes
o Seedless Vascular Plants
o Seeded Plants
Chapter 29.3: Non-Vascular Plants (Bryophytes)
 Bryophytes or non-vascular plants are a group of herbaceous plants that lack vascular tissue
 Bryophyte Gametophytes are horizontally growing carpets
o Larger and longer lived than sporophytes
o Root-like rhizoids anchor gametophytes into ground, they are for support and not for mineral
absorption
o Produce flagellated sperm that are transferred through a medium (i.e. water droplets)
 Bryophyte Sporophytes usually grow vertically
o Dependent on gametophyte for nutrients
o Consist of a foot (connects to gametophyte), seta (a stalk), and a capsule (contains spores)
Chapters 29-30
Yanchen Li
Chapter 29.4: Seedless Vascular Plants
 Plants with vascular systems whose lifecycles are dominated by the sporophyte stage
o Xylem is made out of dead cells that transfer water
o Phloem is made out of living cells and transports nutrients
o Lignin helps support vascular tissue and give the plant its strength
 Produce stalk extensions called Roots and Leaves
o Roots anchor the plant to the ground and absorb water and nutrients
o Leaves increase the plants photosynthetic surface area
 Divided into Megaphylls (broad leaves with branching vascular system) and Microphylls
(pointy leaves with a single vein
 Possess Sporophylls, modified leaves with sporangia
o Plants can be Homosporous (produce bisexual spores/gametophytes) or Heterosporous
(produce spores/gametophytes with different genders)
Chapter 30.1: Seed plants have greatly reduced gametophytes and dominant sporophytes
 Seed plants protect their gametophytes and embryos in Ovules, Pollen, And Seeds
 Seed plants are Heterosporous, they produce two types of spores
o Megaspores germinate into female gametophytes
o Microspores germinate into male gametophytes
 Megaspores develop in ovules
o Ovules consist of a Megasporium (female sporangia), Megaspore, And Integuments (protective
sporophyte tissue that surrounds the megaspore)
 Pollen develops in microsporangia and are dispersed by the wind or by animals, they contain male
gametophytes and produce sperm
 Seeds are protective structures that develop after fertilization and envelop the embryo
Chapter 30.2: Gymnosperms
 Gymnosperms includes conifers and cycads, they bear “naked” seeds without flowers or fruit
 Evolved 360 mya, took a dominant role after the end of the carboniferous
 Produce Cones containing either microsporangia or megasporangia, produce microspores and
megaspores respectively
 After Fertilization (the fusing of a sperm and an egg and the production of zygote) the female cones open
and drop their seeds
Chapter 30.3: Angiosperms
 Originated 140 mya, they are the most diverse and widespread type of plant, includes Eudicots, Monocots
 Characterized by their Flowers and Fruits, make heavy use of animal/insect pollination
o Flowers are reproductive organs containing 4 different Floral Organs
 Sepals lie at base of the flower, usually green, they enclose immature flowers
 Petals are usually brightly colored, used to attract pollinators
 Stamens are microsporophylls, produce pollen and microspores
 Anthers are pollen pods at the tips of stamens
 Filaments connect anthers to the rest of the flower
 Carpels are megasporophylls, contain ovules and produce megaspores
 Stigmas receive pollen and are located at the top of the carpel
 Styles are stalks that connect the stigmas to the ovary
 Ovaries lie at the base of the carpel, contain ovules
 Angiosperms undergo Double Fertilization
o 1 sperm cell from the germinating pollen fertilizes the egg
o A second sperm cell cell fuses with two Polar Nuclei next to the egg cell to produce a polyploid
(usually triploid) Endosperm that nourishes the developing embryo
 Fruits are mature ovaries, they assist in seed protection and distribution
o The Pericarp is a fleshy layer that surrounds the seeds of the fruit, provide protection and
attracts animals
 The evolution of angiosperms allowed the development of complex relationships between plants and
animals, Plants gained directed pollinators and animals gained new food sources
Chapters 29-30
Yanchen Li
Quiz:
Multiple Choice: Pick the Best Answer
1. Which one of these is not a shared characteristic of Charophyceans and Plants?
a) Chlorophyll
b) Rosette shaped cellulose synthesizing complexes
c) Chloroplasts
d) Vascular tissue
2. Which characteristic is not shared by bryophytes, seedless vascular plants, and seed plants?
a) The alternation of generations
b) Apical Meristems
c) Multicellular, dependent embryos
d) Lignified cell walls
3. Bryophytes consist of which phyla:
a) Hornworts, Cycads, Monocots
b) Hornworts, Liverworts, Mosses
c) Conifers, Pterophyta, Mosses
d) Gingko, Lycophyta, Angiosperms
4. Vascular plants are characterized by:
a) Roots, Xylem, Seeds,
b) Phloem, Xylem, Seeds
c) Apical Meristems, Flowers, Roots
d) Xylem, Phloem, Lignin
5. Which of the following is haploid?
a) Cells in the integuments surrounding a developing seed
b) Cells present in the phloem of a fern
c) Endosperm cells
d) Cells in the Protonema of a developing bryophyte
6. Cycads and conifers are part of which group
a) Gymnosperms
b) Angiosperms
c) Bryophytes
d) Lycophytes
7. During fertilization in angiosperms, 2 sperm cells are used up, 1 of these fuses with the egg while the other:
a) Fuses with the polar nuclei to form a triploid endosperm
b) Is discarded
c) Fuses with the polar nuclei to form a diploid endosperm
d) Grows into a new gametophyte
Chapters 29-30
Yanchen Li
8. Which of the following statements about angiosperm flowers are false
a) Petals are usually brightly colored and attract pollinators
b) Stamens contain the pollen producing organs of a plant
c) The stigma is a long tube that connects a plants anthers to the rest of the flower
d) Carpels represent the ovule producing sections of a flower
9. A fossilized plant is discovered from the carboniferous era, it has a deep system of root like extensions, a
tall trunk with vascular tissue, and seems to possess spore producing strobili, based off of these
characteristics, the plant is most likely a:
a) Gymnosperm
b) Liverwort
c) Angiosperm
d) Lycophyte
10. The clade Viridiplantae includes:
a) Chlorophytes, Charophyceans, but not Angiosperms or Bryophytes
b) Bryophytes and angiosperms but not Chlorophytes, Charophyceans
c) Bryophytes, Chlorophytes, Red algae, Angiosperms
d) Bryophytes, Chlorophytes, Angiosperms, Charophyceans
Short answer:
11. The appearance of flowers and fruits was a major factor in the success of angiosperms. List two
advantages that flowers and fruits gave to angiosperms and how they helped angiosperms spread across the
world.
Chapters 29-30
Yanchen Li
Answers:
1. d.
2. d.
3. b.
4. d.
5. d.
6. a.
7. a.
8. c.
9. d.
10. d.
11.
-Flowers produce pollen, which unlike the random wind dispersal found in gymnosperms, can be directed by
animal and insect pollinators. Pollinators will specifically seek out different flowers, assuring that pollen
grains will travel from one flower to another instead of being randomly dispersed by the wind.
-Fruit bearing plants can also disperse their seeds in a similar way, making their fruit a food source for
animals and allowing the animal to transport the seeds inside them for long distances before depositing them
in their droppings.