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Explain the many kinds of liverworts?
Where do they really like it?
- i. There are leafy ones
- ii. The ones around here are very flat
- a. They like it really moist
- i. Best place to find some is along the street; often grow on rocks and streams
- 1. Like moisture
How do they grow?
Form of reproduction?
- a. They grow by forming a fork
- i. The thallus forks
- 1. The older portion dies and the other two newer strsuctures of the fork continue propagation
- b. Asexual reproduction
a. Structure of Thallus (p. 376-377; 369)
ii. Top part is __
iii. There are __ below for __
iv. There are __ that do what __and __(__)
- storage cells
- (trap water between scale and major part of plant)
- rhizoids (absorb)
i. __ by layer of epidermis and layer above storage cells
1. __, which has __
a. The reason they tend to live in moist environments is because __; no way to __; very easy for plants to __
They also have __.
Which species are the most studied?
- Big space
- the pore is permanently open
- close it
- lose water
- gemmae cups
a. Sexual Reproduction
i. Male and female plants
1. Male is __
2. Female is __
- antheridia; they have antheridiophores with anteridia in the top of the structure that is on a little stalk
- archegonia; they have archigoniophores with archegonia, which are on the other side and point downward
a. Why is it pointing downward?
i. Because that’s the orientation because usually, when they are mature, the whole structure is down on the surface of the liverwort; the stalk doesn’t begin to elongate yet
What is the advantage of the archegonia pointing downward?
i. Advantage: archegonia is pointing downward because it allows a small amount of water to allow the sperm to swim down to the egg since they are flagellated
i. Once the egg has been fertilized, then what happens?
1. The sporophyte has a __that is embedded in the __; the __; the __
- the stalk elongates
- tissue of the gametophyte
i. Why is it important for the structure to be at the top of the long stalks; the capsules pointing downward?
1. The spores in the capsule (which develops a pore to open up) can be dispersed; if it were on the bottom, it wouldn’t be able to get dispersed
i. These capsules have __, which moss don’t
1. They are sensitive to __and will do what to help __
a. Hopefully, there’s enough wind to carry it away
- twist with changes
- in humidity
- throw the spores out
1. Forms cups on the surface called __ (kind of __)
2. Eventually form __, which will become gametophytes
3. No __stage
- gemmae cups
1. In the case of mercantia, there are __ and __. Explain the female.
male and female gametophytes
- a. Archegonia are on the underside of the structure (pointing downward) i. Venter, neck, one egg ii. One of the structures will produce numerous archegonia
Explain the male.
- a. ON the male gametophyte, the top contains antheridia
- i. Sterile layer of cells on outside; all cells can develop into sperm
- ii. any antheridia will produce numerous sperm
1. How do sperm get from male thallus to female thallus (plant to plant); and, then after, how do they get to the antheridia?
- a. Water (raindrops)
- i. Splashed on by raindrops
Where is archegonia located?
How do sperm get from where they are to where the antheridium is?
After fertilization, what happens?
Archegonia is up top on the underside
a. What you tend to find is that, when fertilization happens, the stalk is not very tall; the top is basically sittin on the surface of the gametophyte; that’s why they are on the underside
- Because antheridia are relatively short,
- a. Then, the stalk elongates
- i. But, its fertilization, then stalk elongation
1. What is the advantage of the top part (A in the diagram) being up top with the top of the female reproductive structure pointing downward?
- a. Dispersal by the wind
- b. If it were lying on the top, they would fall to the bottom
What do they respond to?
- 1. They twist in response to humidityà throw the spores out
- a. More chance of being dispersed
- b. They twist with the change in humidy
- i. They may twist a little bit more when it’s getting drier
Explain the spacing of the reproductive structures.
- 1. Male reproductive structures are flat on top; rather scalloped
- 2. The archegonium are spaced around (resemble the spokes of an umbrella)