Title: Lecture 9 Outline (Ch. 38)
1(No Transcript)
2Lecture 9 Outline (Ch. 38)
- I. Flower Structures
- II. Life cycle
- III. Gametophyte production Dispersal
- Pollination
- Fertilization
- Germination
- VII. Lecture Concepts
3Angiosperm Overview
4Angiosperm Overview
- In alternation of generations in angiosperms, the
dominant stage is the diploid - sporophyte
- Spores develop inside the flower into tiny,
haploid gametophytes - the male pollen grain and the female embryo sac
(Figure 38.3)
5Angiosperm Lifecycle
6Angiosperm Gametophytes
- Develop with anthers and ovaries, respectively
- Pollen develops from microspores inside the
sporangia of the anther - Within an ovule, a haploid megaspore divides by
mitosis and forms the embryo sac, the female
gametophyte
7Angiosperm Gametophytes
Figure 38.3
8Angiosperm Pollination
- brings female and male gametophytes together
- Fertilization (syngamy) is preceded by
pollination, the placing of pollen on the stigma
of the carpel
9Abiotic Pollination by Wind
Hazel staminate flowers (stamens only)
Hazel carpellate flower (carpels only)
10Pollination by Bees
Common dandelion under normal light
Common dandelion under ultraviolet light
11Pollination by Moths and Butterflies
Anther
Stigma
Moth on yucca flower
12Pollination by Flies
Fly egg
Blowfly on carrion flower
13Pollination by Birds
Hummingbird drinking nectar of poro flower
14Pollination by Bats
Long-nosed bat feeding on cactus flower at night
15Angiosperm Pollination
- The pollen grain produces a pollen tube that
extends down the style toward the embryo sac - Two sperm are released and effect a double
fertilization, resulting in a diploid zygote and
a triploid (3n) endosperm (Figure 38.5)
16Angiosperm Fertilization
17Angiosperm Seed Formation
- develops into a seed containing a sporophyte
embryo and a supply of nutrients (Figure 38.7) - The zygote gives rise to an embryo with apical
meristems and one or two cotyledons - Mitosis of the triploid (3n) endosperm gives rise
to a multicellular, nutrient-rich mass that feeds
the developing embryo and later (in some plants)
the young seedling
18Angiosperm Seed Formation
19The Ovary ...
- develops into a fruit adapted for seed dispersal
- a fruit is a mature ovary that protects the
enclosed seeds and aids in their dispersal via
wind, water, or animals
20Dispersal by Water
Coconut
21Dispersal by Wind
Winged seed of Asian climbing gourd
Dandelion parachute
Winged fruit of maple
Tumbleweed
22(No Transcript)
23The Mature Seed
- The embryo and its food supply are enclosed by a
hard, protective seed coat - The seed enters a state of dormancy
- In some eudicots, such as the common garden bean,
the embryo consists of the embryonic axis
attached to two thick cotyledons (seed leaves) - A monocot embryo has one cotyledon
24Angiosperm Seeds
25Evolutionary Adaptations ...
- the process of germination increases the
probability that seedlings will survive - Germination begins when seeds imbibe water
- this expands the seed, rupturing its coat, and
triggers metabolic changes that cause the embryo
to resume growth - The embryonic root, or radicle, is the first
structure to emerge from the germinating seed - Next, the embryonic shoot breaks through the soil
surface (Figure 38.9)
26Seed Germination (bean)
(a) Common garden bean
Foliage leaves
Cotyledon
Epicotyl
Hypocotyl
Cotyledon
Cotyledon
Hypocotyl
Hypocotyl
Radicle
Seed coat
27Many Plants Can ...
- clone themselves by asexual reproduction
- Asexual reproduction (cloning) is the
reproduction of genetically identical offspring
from a single parent - Apomixis
- production of seeds without fertilization
28Vegetative Reproduction Agriculture
- Humans have devised various methods for asexual
propagation of angiosperms - Cuttings can be taken from many kinds of plants
- They are asexually reproduced from plant
fragments - Grafting is a modification of vegetative
reproduction from cuttings - A twig or bud from one plant can be grafted onto
a plant of a closely related species or a
different variety of the same species
29Vegetative Reproduction Agriculture
- Maize
- Is a product of artificial selection by humans
- Is a staple in many developing countries, but is
a poor source of protein
30Self-Check
Part of plant Function Later becomes Examples
Ovary Contains eggs (ovules) Flesh of fruit Apples, strawberries, coconut meat
Pollen
Ovule
Integuments
Cotyledons
Endosperm
31Lecture 9 concepts
- Describe the parts of a flower. Define
angiosperms. - Explain the process that plants use for
generating pollen and eggs/ovules. - Contrast pollination and fertilization.
- Discuss several types of pollination
methods/pollinators. - Diagram/explain what each part of the fertilized
ovule, coverings, and ovary becomes. - What is the purpose of a fruit? Describe
methods of seed dispersal. - Compare monocot and dicot seeds.
- List the steps of germination. How do seeds know
when to germinate? - How have humans changed the way plants develop?
(many answers) - Write out a list of new terminology and provide
descriptions