2.9.23
Plant Reproduction (Angiosperms)
One Option: Asexual Reproduction
● Plants can make clones of themselves
○ ex) rhizomes, corn, plantlets, asexual seeds
● Advantage: no mate needed, no fertilization, no special structure
● Disadvantage: no species variation, could be wiped out easily
Another Option (Most plants): Sexual Reproduction - lots of variety in angiosperm
flowers
a) Basic Parts of a flower - 4 major flower organs- not necesarrily in all flowers
i) Receptacle- outside of the flower, usually at the bottoms
ii) 1. Sepals (and the whole structure is called the calynx)
iii) 2. Petals (and the whole structure is called the corolla)
iv) 3. Stamen (“males parts”)
1) Anther - where pollen is produced
2) Filament - under Anther -
v) 4. Carpel (“female parts”)
1) Stigma - sticky
2) Style
3) Ovary- eggs are located here
- “Perfect Flowers”- all 4 major organs
- “Imperfect Flower” - missing stamen or carpel
- May be on the same plant (like corn)
- Monoecious = “one house” - one plant you will have male flowers
and female flowers
- May be NOT be on the same plant (like cannabis)
- Dioecious “two houses”
● While some of the pine pollen comes from gymnosperms, some will come from
angiosperms
○ Angio sperms have catkins.
○ Catkins: entire structures of tiny male flowers that produce pollen
○ Live oaks, sweetgum tree
○ Pollen is usually blown by wind from these to the female flowers
● Flowers can also reflect ultraviolet wavelengths of light
○ A) what you and a bee see
○ B) what a bee sees as well and not you (nectar guide)
Alternation of Generations in an Angiosperm
● In angiosperms, the sporophyte is large and long lived; gametophytes are small
(microscopic) and short-lived
○ Mature sporophyte (2n)
○ Sporophyte (2n) produce spores (n) by meiosis
, ○ Spores grow into Gametophytes (n) which produce gametes (n) by mitosis
○ Spores (n) develop into pollen grains (male gametophyte) (
■ Contains sperm (n, gametes)
○ Spores (n) develop into Embryo (carpel) (female gametophyte)
■ Contains the egg (n) and other cells (n)
Timeline of events in Angiosperm reproduction with a little more detail
Pollination:
● Just the delivery of pollen to the stigma (often with the help of pollinators - insects and
birds)
○ Fly pollinated: Smell like rotting flesh (Carrion flower)
○ Hummingbird pollinated flowers: red long tubed with nectar
○ Bee-pollinated flowers: often bright purple
Pollination Syndromes (not illnesses!)
● In most cases, animal pollination is an example of mutualism
○ Pollinators benefit by receiving FOOD, in the form of nectar or pollen
○ Flowering plants benefit because cross-pollination takes place
● Pollination Syndromes: close correlation between the structure of a flower and the size,
shape, and behavior of its pollinators
● Birds: red, unscented, open during the day (hummingbirds - long beak, flowers with long
tube-like petals0
● Bats and moths: white, heavy scent, open at night
● Bees: Purple or yellow flowers with UV pigments too
● Flower- Darwin’s orchid native to Madagascar - extremely long spur with nectary at the
base
● Charles Darwin: hypothesized that it must be pollinated by a moth with a long proboscis
to match, and the other scientists said HA! NO WAY”
○ 40 years later they found
● This is a great example of coevolution
Pollination is not the same as fertilization!
How are pollen
Plants do not have germline cells set aside in development like animals do
● Germline cells = that make gamete cells
● Reproduction in plants occurs when a shoot apical meristem (SAM) converts from
vegetative development to reproductive development
Plant Reproduction (Angiosperms)
One Option: Asexual Reproduction
● Plants can make clones of themselves
○ ex) rhizomes, corn, plantlets, asexual seeds
● Advantage: no mate needed, no fertilization, no special structure
● Disadvantage: no species variation, could be wiped out easily
Another Option (Most plants): Sexual Reproduction - lots of variety in angiosperm
flowers
a) Basic Parts of a flower - 4 major flower organs- not necesarrily in all flowers
i) Receptacle- outside of the flower, usually at the bottoms
ii) 1. Sepals (and the whole structure is called the calynx)
iii) 2. Petals (and the whole structure is called the corolla)
iv) 3. Stamen (“males parts”)
1) Anther - where pollen is produced
2) Filament - under Anther -
v) 4. Carpel (“female parts”)
1) Stigma - sticky
2) Style
3) Ovary- eggs are located here
- “Perfect Flowers”- all 4 major organs
- “Imperfect Flower” - missing stamen or carpel
- May be on the same plant (like corn)
- Monoecious = “one house” - one plant you will have male flowers
and female flowers
- May be NOT be on the same plant (like cannabis)
- Dioecious “two houses”
● While some of the pine pollen comes from gymnosperms, some will come from
angiosperms
○ Angio sperms have catkins.
○ Catkins: entire structures of tiny male flowers that produce pollen
○ Live oaks, sweetgum tree
○ Pollen is usually blown by wind from these to the female flowers
● Flowers can also reflect ultraviolet wavelengths of light
○ A) what you and a bee see
○ B) what a bee sees as well and not you (nectar guide)
Alternation of Generations in an Angiosperm
● In angiosperms, the sporophyte is large and long lived; gametophytes are small
(microscopic) and short-lived
○ Mature sporophyte (2n)
○ Sporophyte (2n) produce spores (n) by meiosis
, ○ Spores grow into Gametophytes (n) which produce gametes (n) by mitosis
○ Spores (n) develop into pollen grains (male gametophyte) (
■ Contains sperm (n, gametes)
○ Spores (n) develop into Embryo (carpel) (female gametophyte)
■ Contains the egg (n) and other cells (n)
Timeline of events in Angiosperm reproduction with a little more detail
Pollination:
● Just the delivery of pollen to the stigma (often with the help of pollinators - insects and
birds)
○ Fly pollinated: Smell like rotting flesh (Carrion flower)
○ Hummingbird pollinated flowers: red long tubed with nectar
○ Bee-pollinated flowers: often bright purple
Pollination Syndromes (not illnesses!)
● In most cases, animal pollination is an example of mutualism
○ Pollinators benefit by receiving FOOD, in the form of nectar or pollen
○ Flowering plants benefit because cross-pollination takes place
● Pollination Syndromes: close correlation between the structure of a flower and the size,
shape, and behavior of its pollinators
● Birds: red, unscented, open during the day (hummingbirds - long beak, flowers with long
tube-like petals0
● Bats and moths: white, heavy scent, open at night
● Bees: Purple or yellow flowers with UV pigments too
● Flower- Darwin’s orchid native to Madagascar - extremely long spur with nectary at the
base
● Charles Darwin: hypothesized that it must be pollinated by a moth with a long proboscis
to match, and the other scientists said HA! NO WAY”
○ 40 years later they found
● This is a great example of coevolution
Pollination is not the same as fertilization!
How are pollen
Plants do not have germline cells set aside in development like animals do
● Germline cells = that make gamete cells
● Reproduction in plants occurs when a shoot apical meristem (SAM) converts from
vegetative development to reproductive development
