Lecture 12 & 13: Vascular Plants Flashcards
L.12
What plants are considered to be Non Vascular? and what common ancestor do they share?
- Mosses, liverworts, homeports
- they share the common ancestor of green algae
L.12
What plants are considered to be Vascular plants? and what are the 2 groups?
First group is: Nonseed
- Ferns
Second group is: Seed
- Flowering plants
- Conifers
L.12
What are the characteristics of extant vascular plants?
- In Vascular tissue there is…
- Xylem: contains lignin which is a strengthening polymer (non-living) and dead hollow cells which act as water pipes
- Phloem: contains living cells and distributes nutrients such as carbohydrates and organic products
L.12
More about vascular plants:
- What do complex multicellular roots do?
- absorb nutrients and provide anchor
L.12
More about vascular plants:
- what do complex multicellular leaves do?
- they have photosynthetic organs
L.12
What are microphylls and megaphylls?
- Microphylls: are a single strand of vascular tissue and are usually small
- Megaphylls: are branching vascular systems and usually large
L.12
More about vascular plants:
- what are sporophylls?
- They are modified leaves that bear sporangia (spore producing organ)
- so when leaves produce spores they become sporophytes
- sporophytes are dominant in life cycle due to increased size and complexity
L.12
Seedless Vascular Plants:
Phylum Lycophyta contains which type of plants?
- quillworts, club mosses, spike mosses (but not mosses!)
L.12
Seedless Vascular Plants:
Phylum Monilophyta contains which type of plants?
-ferns, horsetails, whisk ferns
L.12
What are the characteristics of Seedless Vascular Plants?
- Sporophyte is the dominant form
- Gametophytes are tiny independent plants on or just below the surface
- SVP (Seedless vascular plants) have a Flagellated sperm meaning it must swim in a film of water to reach eggs
- most common in damp habitats and still need water to reproduce
L.12
Phylum Lycophyta characteristics?
- Microphyllous: small leaves
- Carboniferous period (300 mya)
- thrived in warm, moist swamps
became extinct when climate got colder and drier - small lycophytes survived and represent 1000 species today
L.12
Phylum Monilophyta characteristics?
- True ferns are megaphylls with big branching vascular systems
- most successful of extant seedless vascular plants
- produce clusters of sporangia called sori on undersides of leaves
- spores are carried by wind
L.13
What evolutionary adaptations allowed plants to live and diversify under the drying out of the carboniferous period?
- Seeds (embryo w/ stored food) which split into 2 groups…
1. Gymnosperms (naked seed)
2. Angiosperms (Flowering plants)
L.13
Characteristics of Gymnosperms?
- Seed bearing plants are the dominant producers in most terrestrial ecosystems
- a seed consists of an embryo and nutrients surrounded by a protective coating
L.13
RECAP
- Non vascular Bryophytes: Gametophyte is Dominant
- Seedless vascular plants: Sporophyte is Dominant, but gametophyte is independent
- Seed plants have sporophyte dominant and gametophyte independent
L.13
What was the evolution of pollen and seeds?
- Gametophyte dependent on sporophyte- no longer free living
- Pollen- Male gametophyte, protected by pollen grain
- Ovule- female gametophyte, protected by sporophyte
- Seeds- contains next generation sporophyte
L.13
What is a Gymnosperms life cycle look like?
- Mature tree is 2n sporophyte
- sporangia are located on scale-like leaves (sporophytes) in clusters (cones)
- Pollination by wind
- seed dispersal by wind
L.13
Female Gametophyte in Gymnosperms consist of…
- Integuments + megasporangium + megaspore = ovule (egg)
- Megaspor (n) produced w/in megasporangium (2n)
L.13
Male Gametophyte in Gymnosperms consist…
Within the pollen grain…
- Microspore 9n) produced w/in microsporangium (2n)
- Each pollen grain produces a pollen tube for delivering the non flagellated sperm to the egg -> fertilization (sperm doesn’t need water b/c it’s in pollen)
L. 13
Pollen characteristics
- Pollen grains coated with sporopollenin, making them tough
- can withstand drying, Uv and physical damage
- important since male gametophytes have to disperse to pollinate and the fertilize ovule
- The pollen tube discharges sperm into the female gametophyte w/in the ovule (no need for water)
L.13
Pollination…
- the transfer of pollen to the part of a seed plant containing the ovule
- in non seed plants, single celled sperm requires water to swim through
- in seed plants, entire male gametophyte carried inside pollen grain
L.13
In the seed…
- embryo + nutrients + protective coating
- ranging in size which is dependent on gametophyte derived food
- Seed = Dispersal stage
- dispersed by tavel through air, water, in or on animals
- seed has tough coat
- tiny embryo is protected
L. 13
2 Main clades of seeds…
- Gymnosperms: Naked, sperm = seed
2. Angiosperms: container, vessel
L.13
Gymnosperms are characterized by…
and the 3 extant phyla are?
- a seed that is relatively ‘naked’
1. Ginkgophyta: 1 living species
2. Cycadophyta: 130 spp
3. Coniferophyta: 600 spp
