Stamen = filament + anther

1
Angiosperms Production of Male Gametophyte
Stamen filament anther
Meiosis inside anther
male spores
Details follow
2
Angiosperms Production of Male Gametophyte
Meiosis in lily anther 4 haploid
daughter cells, also called pollen tetrads
3
Angiosperms Production of Male Gametophyte
From the point of view of the plant life cycle,
anther male sporangium Each of the 4 pollen
tetrads spore Because of their small size,
they are called microspores.
Pollen tetrads microspores
4
Angiosperms Production of Male Gametophyte
As anther matures, 4 microspores of a tetrad
separate from each other
Haploid nucleus of each microspore undergoes a
single mitotic division
Mitosis
The 2 resulting haploid nuclei become encased in
a thick, resistant wall, forming a pollen grain.
Pollen Grain
5
Angiosperms Production of Male Gametophyte
From the point of view of the angiosperm life
cycle, a pollen grain is an immature male
gametophyte, since it has been produced by the
mitotic division of a spore.
Mitosis
Pollen Grain
6
Angiosperms Production of Female Gametophyte
The pistil (female reproductive portion) is
composed of the stigma, style, and ovary.
7
Angiosperms Production of Female Gametophyte
An ovary may contain a number of ovules.
Meiosis takes place inside the ovules, resulting
in the production of female spores.
Details follow
8
Angiosperms Female Gametophyte
Only one of the haploid spores resulting from
meiosis in the ovule matures. It undergoes 2
rounds of mitosis to form the embryo sac, which
has 8 haploid nuclei.
Embryo sac female gametophyte
9
Alternation of Generations Angiosperms
To complete the life cycle, the gametes produced
by the male and female gametophyte must unite,
restoring the diploid sporophyte.
Female gametophyte embryo sac
Immature male gametophyte pollen grain
10
Fertilization and Embryo Formation
Pollen grain landing on stigma of ovary pollen
tube growth
11
Fertilization and Embryo Formation
2 haploid cells of pollen grain are called the
generative cell and the tube cell
Pollen tube growing from a pollen grain
12
Fertilization and Embryo Formation
As pollen tube grows towards ovule, nucleus of
generative cell divides by mitosis, producing 2
haploid sperm
13
Fertilization and Embryo Formation
The pollen grain, along with the pollen tube
containing 2 sperm, is the mature male
gametophyte.
14
Fertilization and Embryo Formation
Pollen tube continues to grow, entering ovule
through opening called the micropyle
15
Fertilization and Embryo Formation
One of the sperm fertilizes the egg, producing a
diploid zygote. This zygote will divide and
differentiate, forming the sporophyte plant. The
angiosperm life cycle has been completed.
The other sperm will fuse with the 2 central
haploid nuclei in the embryo sac, producing a
triploid nucleus.
These events are called double fertilization.
16
Fertilization and Embryo Formation
Tissue that develops from the triploid nucleus
endosperm. Energy stored in this tissue
nourishes the developing embryo.
17
(No Transcript)
18

• We have derived many medical compounds from the
  unique secondary compounds of plants.
• More than 25 of prescription drugs are
  extracted from plants, and many more medicinal
  compounds were first discovered in plants and
  then synthesized artificially.

19
Evolutionary Trends in Plant Life Cycles
Angiosperms demonstrate an evolutionary trend in
which the gametophyte is further reduced in size,
and increasingly dependent upon the sporophyte.
20
Development of the Young Dicot Sporophyte
Developing zygote, endosperm, and other tissues
of the ovule eventually become a seed
Bean
Corn
Example follows
21
Development of the Young Dicot Sporophyte
developing ovules
Continued
Longitudinal section through Capsella ovary
22
Development of the Young Dicot Sporophyte
Suspensor
Developing embryo proper
endosperm
Continued
23
Development of the Young Dicot Sporophyte
As development continues, cotyledons fill entire
embryo sac
As the embryo develops, cotyledons begin to grow
24
Development of the Young Dicot Sporophyte
Here is a longitudinal section of an ovary with a
number of well-developed ovules inside.
25
Development of the Young Dicot Sporophyte
Todays lab examine external and internal
structure of a mature ovule, i.e. a seed
26
Seed Germination
Germination and seedling development in beans
27
Common Plant Cell Types
Collenchyma
Sclerenchyma
Fibers
Sclereids
Parenchyma
28
Common Plant Cell Types
cork cells important in bark tissue
sieve tube members companion cells important
in phloem tissue
29
Primary vs. Secondary Growth
Primary growth growth in length, e.g. in seed
germination
Secondary growth growth in girth (width), e.g.
Tilia stem cross-section
30
Primary Meristems
Whether they are involved in primary or secondary
growth, all plant cells and tissues arise from
three primary meristems protoderm ground
meristem procambium
Meristem plant tissue that remains embryonic
as long as the plant lives, allowing for
indeterminate growth
31
Primary Secondary Growth in a Woody Stem
Primary meristems Protoderm Ground
meristem Procambium
Primary Tissues Epidermis
Pith Ground Cortex Primary
phloem Primary xylem
Lateral Meristem
Secondary Tissues
Periderm
Cork cambium cork
2o phloem 2o xylem
Vascular Cambium
32
Tissue Arrangement in Typical Herbaceous Stems
Epidermis
Cortex
Vascular bundle
Phloem
Xylem
Fascicular cambium
Interfascicular cambium
Pith
Monocot
Dicot
33
Secondary Growth in a Woody Dicot
vascular cambium produces 2o xylem ( wood) to
the inside, 2o phloem to the outside
34
Tilia cross-section
Vascular cambium
Primary xylem
Secondary phloem
Secondary xylem
Phloem ray
Pith
35
Cell Types in Secondary Phloem Ray of Bark
Sieve tube members
Companion cells
Fibers
36
Simple versus Compound Leaves
37
Generalized Leaf Anatomy
38
Typical Dicot Leaf X-Section
Cuticle
Epidermis
Palisade Parenchyma
Vascular bundles
Guard Cells
Spongy Parenchyma
Stoma
39
Typical Monocot Leaf X-Section
Bundle sheath cell
Midvein
Epidermis
Vein
Phloem
Xylem
Stoma
Bulliform Cells
40
Leaf Stomata Allow Gas Exchange
Guard cells with chloroplasts
Stomata in Zebrina leaf epidermis
Stoma
Subsidiary cells
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)