Botany – Flowers,
Fruits, and Seeds
_____________________________
from a seed and ends with the production
of new seeds.
A.
Annuals- complete life cycle in _____________________________.
All
roots, stems and leaves of the plant die annually. Only the dormant
seed
bridges the gap between one generation and the next.
1. Examples –
B. Biennials- complete life cycle in _____________________________.
1.
First season growth results in a small rosette of leaves near the
soil surface.
2.
During the second season's growth stem elongation, flowering
and seed formation occur followed by the
entire plant's death.
3.
Examples –
C.
_____________________________- complete life cycle in more than
two
years.
1.
Plants that persist for many growing seasons.
a. Examples –
2.
In other perennials, the top portion of the plant dies back each
winter and regrows the following spring
from the same root system.
a.
Examples –
II. Flowering Plants- all belong to Phylum ____________________________
A. This division is subdivided into the
following classes…
B. Class
_____________________________ (formerly known as
Monocotyledonae)
1.
We commonly refer to them simply as monocots
2.
What does monocot mean?
a.
Mono, of course, means __________________________
b.
Cot is referring to a food storage structure within the seed
known as the _____________________________.
c.
Monocots have one cotyledon in their seed.
3. Examples –
D.
Class _____________________________ (formerly known as
Dicotyledonae)
1.
We commonly refer to them simply as dicots.
2.
Dicots have _____________________________
cotyledons in
their seeds.
3.
Examples –
E.
The
true difference between monocots and dicots is the number of
cotyledons
in their seeds, however they generally have the following
characteristics…
|
DICOTS |
MONOCOTS |
||
|
1. |
Seed with |
1. |
Seed with |
|
2. |
Flower parts
in |
2. |
Flower parts
in |
|
3. |
Leaf with |
3. |
Leaf with |
|
4. |
Vascular and
cork cambia |
4. |
Vascular and
cork cambia |
|
5. |
Stem vascular
bundles |
5. |
Stem vascular
bundles |
|
6. |
Pollen grains
usually have |
6. |
Pollen grains
usually have |
|
7. |
Root core consists
of |
7. |
Root core
consists of |
III. Flower Structure- Flowers develop from buds which
originate from
_____________________________.
Often the terminal bud of a plant becomes
the flower bud.
Image modified
from: http://www.auburn.edu/academic/classes/biol/1030/bowling/lecturenotes/topic7_files/image004.jpg
A. A typical flower has the following parts…
1. Peduncle-
2. Receptacle-
3. _____________________________- three or more plant parts
encircling another
plants parts (already seen in leaves).
4. Sepals-
a.
_____________________________- whorl of sepals,
usually
3-5 sepals.
5. _____________________________- usually brightly colored
appendages inside the
sepals used to attract pollinating insects.
Many have special
markings that show up in the UV range of
eyesight of bees.
a.
_____________________________- whorl of petals.
Often
missing in wind-pollinated flowers.
6.
Petals or sepals may be fused together to form a tube-like
corolla or calyx.
7.
Pistil-
Female
part of the flower that
consists of the following structures…
a. Stigma-
(where pollen will land)
b. Style-
c. Ovary-
Later becomes the _____________________________.
Ovaries
can be classified as …
1)
_____________________________- calyx and
corolla
are attached to the receptacle at the base
of
the ovary.
2) _____________________________-
receptacle
grows
up around the ovary so that the calyx and
corolla
appear to be attached above the ovary.
d. Ovule-
Later becomes the _____________________________.
e. Carpels-
In general, each carpel holds one ovule.
8. Stamen-
a.
Anther-
b. Filament-
B.
There is an easy memory device to distinguish male & female flower
parts.
1.
C_____________________________- clusters
of flowers growing from a
single
peduncle.
1.
The peduncle is divided into many
_____________________________, one to each flower.
2.
Examples –
IV. Fruits
A.
A
Fruit is an _____________________________
that has developed
and
matured.
1.
Usually,
the development of fruits requires fertilization of an
ovule
by a ______________________________________.
2.
The
pollen grain produces hormones that may cause fruit
development.
3.
Usually,
hormones released from the developing seed promote
fruit
development.
4.
These
hormones stimulate the production of more hormones by
the
ovary wall.
B.
Fruit
tissues form regions that are often difficult to distinguish. The
regions
of a mature fruit include…
Image modified
from: http://visual.merriam-webster.com/images/plants-gardening/plants/fruits/stone-fleshy-fruit.jpg
1. Exocarp-
2. _____________________________- layer of tissue next to
seed.
a. May be hard as in the pits of peaches,
apricots, etc.
b. May be papery as in apples.
c. May be indistinguishable from
mesocarp.
3. Mesocarp-
4.
_____________________________- collective name for all fruit
tissue
regions; usually very thin in dry fruits.
C.
Types of fruits…
1. _____________________________- fruit develops without
fertilization
(commercial bananas, navel oranges)
2. Fleshy fruits- mesocarp is at least partly fleshy at maturity
3. Simple Fleshy Fruits- derived from a single pistil
a. Drupe- single seed enclosed by a hard
endocarp and soft
pericarp (ex. Coconut)
a.
Berry- usually contains more than one seed, and the
entire
pericarp is fleshy
1)
True
(tomatoes,
grapes, peppers)
2)
Other berries- develop from inferior ovary and
incorporate
other flower parts into the fruit
(blueberries,
cranberries, bananas)
b.
Pepo- fruit with thick rind, usually with many seeds
(pumpkin
family)
d. Hesperidium-
berry with leathery skin containing oils.
Outgrowths of the ovary wall become
sac-like and filled with
juice (citrus family)
c.
Pome- flesh is derived from an enlarged receptacle from
around
the ovary. Endocarp is papery or
leathery
(apples,
pears)
4. Aggregate Fruits- derived from a single flower with several to
many pistils. Individual
pistils develop into small drupes or other
fruitlets, but mature as
a clustered unit on a single receptacle
(blackberries,
raspberries, strawberries)
5.
Multiple Fruits- derived from several to many flowers
on a
single
inflorescence. Fruitlets from each
pistil merge
together
to form the aggregate fruit (mulberries, pineapples,
figs)
6.
Dry Fruits- mesocarp is dry at
maturity
a. Dry Fruits that split
at maturity:
1) Follicle- splits along one side or seam
to expose
seeds within (larkspur, columbine, milkweed)
2) Legume- splits along two sides or seams
to
expose
seeds (beans, peas, lentils)
3) Silique/silicle- split along two sides;
seeds are
born
on a central partition. Small siliques are called
silicles
(broccoli, cabbage, mustards, radish)
4) Capsule- two or more carpels that split
in a variety
of
ways; most common dry fruit (poppy, iris, orchid,
lily)
b. Fruits
that don’t split at maturity
1)
Achene- has a single seed attached
at the base to
the
surrounding pericarp (sunflower, buttercup,
buckwheat)
2) Nut- similar to an achene, but with
larger and
harder
pericarp; develops with a cup or cluster of
bracts
at the base (acorns, hazelnuts/filberts, hickory
nuts, chestnuts). Most “nuts” are not true nuts,
but
drupes,
legume, or seeds.
3) Grain/caryopsis- pericarp is tightly
united with the
seed
and cannot be separated from it. (grass family)
4) Samara- pericarp forms a wing or
membrane
(maple,
ash, elm)
5) Schizocarp- twin fruit that breaks down
into single
fruits
(mericarps) when dry (parsley
family—carrot,
anis,
dill)
V. Seed Dispersal- Seeds are produced inside fruits.
Ultimately, the seed must
be released and
dispersed to prolong the species. In some cases, individual
seeds are
dispersed.
A.
Wind-
seeds have adaptations that allow them to be carried by wind
Currents
(samaras, some achenes, and capsules)
B.
Animals
1.
Some seeds are dispersed when animals eat the fruits.
a.
The seeds pass through the animal’s digestive system
and emerge in the feces.
b.
This is perfect for the seed, it’s deposited in fertilizer!
2.
Other seeds and fruits become attached to the animals’ coats,
skin, or feathers and fall off later.
3.
Some seeds are buried by animals as food stores and then
germinate.
C.
Water- some seeds have air pockets inside or around them that allow
them
to float.
D.
Miscellaneous-
1.
Some seeds are forcibly ejected from fruits.
Watch
this video: https://youtu.be/nHqHSpZhjeY
2.
Others simply fall around the plants.
3.
Filarees corkscrew themselves into the ground as the humidity
changes.
VI. Seeds and germination- Seeds contain embryonic plants in a
_____________________________ state.
A. Dry seeds can remain viable for many years,
only germinating when
conditions
are right.
1.
The
record had been 1,200 years for a Chinese Sacred Lotus tree.
a.
When
this seed germinated, it had a different number of
petals
than modern lotus trees. This is just
another piece
of
evidence for evolution.
b.
UPDATE: The Judean
Date Palm - the oldest known tree seed successfully germinated, and also the
only living representative of the Judean date palm, a tree extinct for over 800
years, which was once a major food and export crop in ancient Judea.
1) A cache
of date palm seeds was found preserved in a jar during the 1963-1965
excavations at Herod the Great’s palace in Masada, Israel. They had experienced
a very dry and sheltered environment for centuries. Radiocarbon dating
confirmed the seeds dated
from 155 BC to 64 AD. The seeds were held in storage for 40 years at
Bar-Ilan University until 2005 when they were pretreated in a fertilizer and
hormone-rich solution. Three seeds were planted in the Arabah desert in
southern Israel. Eight weeks later one sprouted. It is a male plant that has
bloomed, produced pollen, and reached 2 meters tall by the summer of 2010.
2.
Some seeds require chemical or physical __________________
of the seed coat before they germinate.
3.
Others need a brief treatment with fire.
a.
Example –
4. Different seeds have specific environmental
cues that cause
germination.
a.
Example – I have to refrigerate or freeze some of my
seeds to get them to germinate (ex __________________)
B.
Seed
Structures
Image by Mrs.
Estlack.
1. Funiculus
–
a.
The
funiculus functions as an “umbilical cord,” allowing
the
transfer of food and energy from the parent plant into
the
developing seed.
2. Seed
coat –
a. The seed coat develops from the
_____________________________ of the
ovule.
3. Hilum
–
(this
is the funicular scar).
4. Micropyle
–
a.
Later, when the seed matures and starts to germinate,
the micropyle serves as a minute pore through which
water enters.
5. Cotyledon
–
(Remember that the baby plant can’t
photosynthesize & make its
own food until it emerges from the
soil. Therefore, the seed must
store some food for the baby plant until
it can fend for itself.)
a.
_____________________________ – In some seeds,
the
cotyledon(s) play no significant role in food storage.
The
endosperm serves as the bulk of the
food-storage
tissue
(e.g. corn)
6. Embryonic
plant - young sporophyte consisting of epicotyl,
hypocotyl,
radicle, and one or more cotyledons
7. Plumule
–
They become the first true leaves of the
plant.
a.
_____________________________ - protective first leaf
sheath
surrounding epicotyl in grasses
8.
Epicotyl –
9. Hypocotyl
-
10. Radicle
–
a.
_____________________________ – protective sheath
around
radicle in grasses
C.
Germination-
1. Viability-
a.
In
some seeds, damage to the embryo or seed coat can
result
in loss of viability.
2.
Dormancy-
a.
Some
seeds must be dormant for a set period of time
before
they germinate
1)
helps
prevent germination while still on parent
plant.
b. The fruits of many plants produce hormones
that induce
dormancy.
1) Once, the seeds are free of the fruit, the
hormones
no longer
have effect.
c. Some plants have no dormancy and may
germinate
inside
the fruit (mangrove).
3.
Imbibition-
a.
Usually the first step in germination.
b.
Energy reserves in the cotyledons or endosperms are
used for growth until the new plant
emerges from the soil
and can start photosynthesis.