Transcript chapter25

The Plant Kingdom:
Flowering Plants
Chapter 25
LEARNING OBJECTIVE 1
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Summarize the features that
distinguish flowering plants from
gymnosperms
KEY TERMS
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ANGIOSPERM
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Traditional name for flowering plants
A large, diverse phylum of plants that form
flowers for sexual reproduction and produce
seeds enclosed in fruits
Flowering Plants
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Like gymnosperms:
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Flowering plants have vascular tissues and
produce seeds
Unlike gymnosperms:
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Ovules of flowering plants are enclosed
within an ovary
KEY TERMS
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OVULE
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Structure in the ovary that contains a female
gametophyte and develops into a seed after
fertilization
OVARY
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Base of a carpel or fused carpels that
contains ovules and develops into a fruit after
fertilization
Orange Fruit Development
LEARNING OBJECTIVE 2
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Describe the ecological and economic
significance of the flowering plants
Ecology and Economy
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Our survival as a species depends on
flowering plants
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Major food crops
Products
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Cork, rubber, tobacco, coffee, chocolate,
aromatic oils for perfumes
Valuable lumber
Fibers and medicines
Economic Botany
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Subdiscipline of botany that deals with
plants of economic importance
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Most of these are flowering plants
LEARNING OBJECTIVE 3
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Distinguish between monocots and
eudicots, the two largest classes of
flowering plants
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Give specific examples of each class
KEY TERMS
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COTYLEDON
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The seed leaf of a plant embryo, which may
contain food stored for germination
KEY TERMS
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MONOCOT
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One of two main classes of flowering plants;
monocot seeds contain a single cotyledon
Monocots have floral parts in threes
Monocots include grasses, orchids, irises,
onions, lilies, palms
KEY TERMS
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EUDICOT
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One of two main classes of flowering plants;
eudicot seeds contain two cotyledons
Eudicots have floral parts in fours or fives
Eudicots include oaks, roses, mustards, cacti,
blueberries, sunflowers
Monocots and Eudicots
Petal
Sepal
Anther of
stamen
Stigmas of
pistil
(a) Monocots, such as this nodding trillium
(Trillium cernuum), have their floral parts in threes.
Note the three green sepals, three white petals, six
stamens, and three stigmas (the compound pistil
consists of three fused carpels).
Fig. 25-2a, p. 488
Petal
Anther of
stamen
Pistils
(b) Most eudicots such as this Tacitus
bellus have floral parts in fours or fives.
Note the five petals, 10 stamens, and five
separate pistils. Five sepals are also present
but barely visible against the background.
Fig. 25-2b, p. 488
LEARNING OBJECTIVE 4
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Briefly explain the life cycle of a
flowering plant
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Describe double fertilization
Life Cycle
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Flowering plants undergo an alternation of
generations:
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Sporophyte generation is larger and
nutritionally independent
Gametophyte generation is reduced to only a
few microscopic cells
KEY TERMS
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DOUBLE FERTILIZATION
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A process in the flowering plant life cycle in
which there are two fertilizations
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One results in formation of a zygote
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Second results in formation of endosperm
KEY TERMS
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ENDOSPERM
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The 3n nutritive tissue formed at some point
in the development of all angiosperm seeds
Life Cycle: Flowering Plants
Pollination
Developing pollen
tube of mature
male gametophyte
Each microspore
develops into a
pollen grain 5
6
Pollen grain
(immature male
gametophyte)
Microspore
Tetrad of
microspores
3
Megaspore
HAPLOID (n)
GAMETOPHYTE
GENERATION
Meiosis
4
Embryo sac
(mature
female
gametophyte)
Pollen
tube
2
Ovary
Megaspore
mother cell
DIPLOID (2n)
SPOROPHYTE
GENERATION
Megasporangium
(ovule)
Polar
nuclei
Egg
nucleus
Two sperm
cells
Double fertilization
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Endosperm (3n)
Zygote (2n)
Fruit
8
Embryo
Microspore mother
cells within
microsporangia
Anther
Seed
Seed coat
1 Seedling
Flower of mature
sporophyte
Fig. 25-3, p. 490
Pollen Grains
LEARNING OBJECTIVE 5
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Discuss some of the evolutionary
adaptations of flowering plants
Adaptations of Flowering Plants 1
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Reproduce sexually by forming flowers
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Form seeds within fruits after double
fertilization
Adaptations of Flowering Plants 2
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Have efficient water-conducting vessel
elements in xylem and carbohydrateconducting sieve-tube elements in
phloem
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Have pollen grains transported by wind,
water, insects, other animals
KEY TERMS
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APOMIXIS
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A type of reproduction in which fruits and
seeds are formed asexually
Adaptability of Flowering Plants
LEARNING OBJECTIVE 6
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Trace the evolution of flowering plants
from gymnosperms
Evolution of Flowering Plants
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Probably descended from ancient
gymnosperms with specialized features
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leaves with broad, expanded blades and
closed carpels
Probably arose only once
Drimys piperita Carpel
Carpel
Fused
margin
Ovules
Stigma
Ovary
Style
Stigma
(a) The carpel resembles a folded
leaf in which the ovules borne on
its upper surface are enclosed.
(b) A cross section of the
carpel, cut along the dashed
line in (a).
Fig. 25-6, p. 493
Fossil Angiosperms
Pistils
Carpel
Ovule
(a) The oldest known fossil
angiosperm. This fossil of
the extinct plant Archaefructus
shows a carpel-bearing
stem. It was discovered in
northeastern China and is
about 125 million years old.
Scars on
reproductive
axis
(b) The fossilized flower of the extinct plant Archaeanthus
linnenbergeri, which lived about 100 mya. The
scars on the reproductive axis (receptacle) may show
where stamens, petals, and sepals were originally
attached but abscised (fell off). Many spirally arranged
pistils were still attached at the time this flower was
fossilized.
Fig. 25-7, p. 494
Evolution of Flowering Plants
Eudicots
Monocots
Core
Angiosperms
Magnoliids
Star anise
Water lilies
Amborella
Basal Angiosperms
Evolution of
vessel elements
Evolution of
flowering plants
(a) One hypothesis of relationships among the flowering plants, based on fossil and
molecular evidence. Amborella, water lilies, and star anise are living plants
whose ancestors apparently branched off the angiosperm family tree early. These early
groups were followed by the magnoliids, the monocot branch, and the eudicots.
Fig. 25-8, p. 495
LEARNING OBJECTIVE 7
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Distinguish between basal
angiosperms and core angiosperms
KEY TERMS
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BASAL ANGIOSPERM
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One of three groups of angiosperms thought
to be ancestral to all other flowering plants
CORE ANGIOSPERM
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Group including most angiosperm species
Divided into three subgroups: magnoliids,
monocots, and eudicots
KEY TERMS
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MAGNOLIID
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One of the groups of flowering plants
Core angiosperms once classified as “dicots,”
but molecular evidence indicates they are
neither eudicots nor monocots
Includes species in magnolia, laurel, and
black pepper families, several related families
LEARNING OBJECTIVE 8
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Briefly describe the distinguishing
characteristics and give an example or
two of each of the following flowering
plant families: magnolia, walnut,
cactus, mustard, rose, pea, potato,
pumpkin, sunflower, grass, orchid, and
agave
Flowering Plant Families 1
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More than 300 families
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Magnolia family
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Important ornamentals and source of timber
Examples: southern magnolia, tuliptree
Magnolia Family
Fig. 25-9, p. 497
Flowering Plant Families 2
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Walnut family
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Provides nuts for food, wood for furniture
Examples: English walnut, black walnut, pecan
Cactus family
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Important as ornamentals
Examples: prickly pear, Christmas cactus
Walnut Family
Female
flowers
Catkin
of male
flowers
Young tree
Compound leaf
(a) The pinnately compound leaves and green fruits of black
walnut (Juglans nigra) make the tree easy to recognize.
Fruit
(a drupe)
Fruit with husk
removed to show
hard stone
Fig. 25-10a, p. 498
Fig. 25-10b, p. 498
Fig. 25-10c, p. 498
Cactus Family
Stamens
Stigma
Petals
(c) Cactus flowers contain numerous sepals, petals, and
stamens. The compound pistil consists of two to many fused
carpels. In this photo of a prickly pear cactus (Opuntia
humifusa), the petals, stamens, and stigma are evident.
Fig. 25-11c, p. 499
Flowering Plant Families 3
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Mustard family
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Many important food crops
Examples: cabbage, broccoli, cauliflower,
turnip, mustard
Rose family
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Commercially important fruits and ornamentals
Examples: apple, pear, plum, cherry, apricot,
peach, strawberry, raspberry, rose
Mustard Family
Pistil
Stamen
Petal
Sepal
(a) A typical mustard flower, showing the
four petals arranged in the shape of a cross.
Fig. 25-12a, p. 501
Mustard Family
Mustard Family
Mustard Family
Rose Family
Rose Family
Rose Family
Flowering Plant Families 4
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Pea family
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Important food crops
Examples: garden pea, chick pea, green
bean, soybean, lima bean, peanut, red clover,
alfalfa
Pea Family
Young
fruit
Banner
Compound leaf
(three leaflets)
Sepal
Wing
Corolla
Keel (two
fused
petals)
(b) Close-up of a bean flower, showing
its irregular corolla shape.
Remnants of sepals
(and sometimes petals
and stamens)
Remnants of
Pod (fruit)
Seeds stigma and style
(c) The bean fruit, a legume, is
opened to show the seeds.
(a) Part of a common bean (Phaseolus vulgaris)
plant, showing flowers and developing fruits.
Fig. 25-14a-c, p. 503
Pea Family
Pea Family
Flowering Plant Families 5
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Potato family
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Important food crops and chemicals used as
drugs
Examples: potato, tomato, green pepper,
eggplant, petunia, deadly nightshade
(belladonna)
Potato Family
Flowering Plant Families 6
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Pumpkin family
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Food crops
Examples: pumpkins, melons, squashes,
cucumbers, cantaloupe, honeydew,
muskmelon, cucumber, watermelon
Pumpkin Family
Petals
fused into
bell shape
Stigma
Style
Ovary
(a) Cutaway view of a female squash flower. Note
the inferior ovary located beneath the point of
attachment of the sepals and petals.
Fig. 25-16a, p. 505
Pumpkin Family
Anthers
(b) Cutaway view of a male squash flower. Note
the united anthers.
Fig. 25-16b, p. 505
Pumpkin Family
Flowering Plant Families 7
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Sunflower family
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One of the largest families of flowering plants
Examples: chrysanthemums, marigolds,
sunflowers, daisies, and some food plants
such as lettuce, globe artichokes
Sunflower Family
Ray floret
Disc floret
a) Head of a sunflower (Helianthus annuus).
Fig. 25-17a, p. 506
Ray floret
Disc floret
Stigmas
Anther
Corolla
Ovary
(c) Female ray floret.
(d) Bisexual disc floret.
Fig. 25-17cd, p. 506
Flowering Plant Families 8
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Grass family
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Most important family of flowering plants from
the human standpoint
Examples: rice, wheat, corn, oats, barley, rye,
sugarcane, bamboo
Grass Family
Anther
Inflorescence
Palea
Filament
Feathery
stigma
Ovary
Blade
Reduced petals
Sheath
Lemma
Stolon
Rhizome
Fibrous root
system
(a) The growth habit of a representative grass plant. Grass flowers, which
are wind pollinated, are highly modified. Note, for example, the long,
feathery stigmas, adapted to efficiently catch wind-borne pollen.
Fig. 25-18a, p. 507
Flowering Plant Families 9
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Orchid family
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One of the largest families of flowering plants;
contains a greater variety of flowers than any
other family
Example: the vanilla orchid
Agave family
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Best known for ornamentals
Examples: century plant, sisal hemp,
bowstring hemp
Orchid Family
Aerial roots
(a) The moth orchid (Phalaenopsis hybrid)
has photosynthetic aerial roots.
Fig. 25-19a, p. 509
Pseudobulbs
(b) A Cymbidium hybrid has pseudobulbs
that function as storage organs.
Fig. 25-19b, p. 509
Petal
Sepal
Lip (modified
petal)
(c) Orchid flowers, such as Dendrobium, are
distinctive in that the third petal forms a lip.
Fig. 25-19c, p. 509
Agave Family
Animation: Monocot Life Cycle
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