1. Reproduction in Angiospermophytes (flowers)
What is… a flower?
How does this work?
A close look at a seed…
Refer to chapter 27 in text.

2. The flower isn’t the only reproductive path for many angiosperms
What is… a flower?
The flower isn’t the only reproductive path for many angiosperms
(alternatives include bulbs, tubers, adventitious roots,
rhizomes and apomixis, as in dandelions)
but flowers allow genetic mixing.… It’s about sex.

3. Why are these two here side by side?

4. Parts of an animal-pollinated eudicot flower: Peduncle Receptacle
“draw and label…”
Parts of an animal-pollinated
eudicot flower:
Peduncle
Receptacle
Sepals, forming a calyx
Petals, forming a corolla
(attracts right pollinator)
Male:
stamen
anther
filament
Female:
pistil/carpel
stigma
style
ovary
(this is a superior ovary…)
How will you recall which is which?

5. perfect (bisexual) flowers bilateral symmetry↓
variations on a theme… :
radial symmetry ↑
perfect (bisexual) flowers
bilateral symmetry↓
inflorescence ↑(cluster)
composite (looks like one) of incomplete flowers↑
healing.about.com/.../SuSunflower.htm
single-sex
flowers:
←dioecious
(separate
plants)
monoecious
(different
flowers,
one plant)
e.g.pumpkins →

6. When to flower?
Some are triggered by day length:
long-day plants flower when the nights get shorter (spring/summer),
short-day plants flower as the nights get longer
(fall).
Phytochrome: a plant pigment that detects visible light.
- The red absorbing form (Pr) shifts to the far-red absorbing form (Pfr)
when red light is applied (and vice versa).
- In the dark Pfr gradually devolves back to Pr.
Pfr promotes flowering in long-day plants,
and inhibits flowering in short-day plants.

8. Many flower designs are the result of coevolution
How does this work?
Many flower designs are the result of coevolution
with a mutualistically symbiotic pollinator….

9. … though some flowers are designed, with everything hanging out,
for wind pollination.
Pollination: transfer of pollen
to the part of a seed plant
containing the ovules.
not to be confused with
Fertilization: the union of
haploid gametes to produce a
diploid zygote.

10. - A pollen grain from an anther lands on the stigma.
- A pollen grain from an anther lands on the stigma.
- A pollen tube germinates and grows down the style to the ovule.
- The pollen tube delivers two pollen nuclei to the ovule….

11. Double Fertilization: The pollen tube delivers 2 sperm nuclei to the
micropyle.
One merges with a
female nucleus,
making a diploid
zygote.
The other merges
with two female
nuclei (polar bodies)
to form a triploid
endosperm nucleus.

12. “Draw and label a diagram showing the external
A close look at a seed…
“Draw and label a diagram showing the external
and internal structure of a named dicotyledonous seed.”
Embryo shoot/
Micropyle
/Embryo root
/Testa
In dicots this is embryo leaf,
consisting of endosperm.
In monocots this sheaths embryo leaf,
transferring nutrients from endosperm.
Gymnosperms have 2 to 24 cotyledons,
similar to the monocot in design.
In the case of synonyms, the one in italics is British.

13. Germination: breaking dormancy and starting to grow,
How does this seed thing work?
Germination: breaking dormancy and starting to grow,
when conditions are “right”…
Different seed have different triggers:
If the area is seasonally dry,
it might require heavy rain.
If the area is subject to fires,
it might require fire (that takes out competitors).
If it is an area with extreme winters,
it might require a long cold spell to break dormancy.
If it is a small seed,
it might require light, to indicate it is not deeply buried.
If it is distributed by fruit-eating animals,
it might require exposure to digestive juices.

14. Whatever the cues that the timing is right,
all seeds follow some common steps:
1. Imbibition: water intake -
loosens testa and starts metabolic processes.
2. Gibberellin manufacture -
this plant hormone, made in the cotyledon, starts
3. Amylase production –
an enzyme which breaks starch down into maltose, which
moves to the embryo and provides energy for
4. emergence of the radicle,
and growth of the plant.

15. biology.unm.edu/.../FloweringPlants.htm

16. How do plants detect day length?
What does a dicot seed look like,
and how does it germinate?
What are the parts of an
animal-pollinated flower?
(Draw one.)
What is the purpose of flowers?
What kinds of flowers are there?
Distinguish between pollination,
fertilization,
and seed dispersal

17. vocabulary list peduncle perfect zygote receptacle inflorescence
polar bodies
sepal
composite
embryo shoot
calyx
complete
epicotyl
petal
incomplete
hypocotyl
corolla
dioecious
micropyle
stamen
monoecious
radicle
anther
long-day plant
embryo root
filament
short-day plant
cotyledon
pistil
phytochrome
seed coat
carpel
pollination
testa
stigma
fertilization
germination
style
pollen grain
dormancy
ovary
pollen tube
imbibition
radial symmetry
double fertilization
gibberellin
bilateral symmetry
amylase