Lecture 8- Plant Diversity I Flashcards
Veridiplantae Members and Shared Derived Trait
All green plants: Chlorophytes, charophytes, land plants
Derived trait: Cellulose cell walls
Streptophyta Members and adaptations
Charophytes and land plants
Adaptations for land- Many charophytes live at edges of ponds
Sometimes dries out -> selection favors survival on dry land
Streptophyta Shared Derived Traits
- Streptopollenin
Polymer, surrounds zygote
Prevents desiccation - Structure of flagellated sperm
- Cell plate
Derived Traits Land Plants
- Alternation of Generations
-> 2 multicellular life stages
Haploid gametophyte- produces gametes by mitosis
Diploid sporophyte- produces spores by meiosis - Multicellular, Dependent Embryo
2n embryo retained within tissue of female gametophyte. Nutrients transferred from parent. - Walled Spores Produced in Sporangia
Sporangia: Multicellular organs that produce spores
Sporocytes: Diploid cells, undergo meiosis-> haploid spores
Spores: Haploid reproductive cells
Spore wall contains sporopollenin
Resistant to harsh conditions - Multicellular Gametangia
Gametangia: Multicellular gamete-producing organs- 2 types
Archegonia: Produce eggs, site of fertilization
Antheridia: Produce and release sperm - Apical Meristems
Plants don’t move, do elongate
Apical meristems: Localized regions of cell division at tips of roots and shoots
Cells differentiate from apical meristems - Cuticle
Waxy covering over all above-ground parts
Prevents desiccation
Provides some protection from microbes
Does not allow for gas exchange - Stomata (singular= stoma)
Tiny openings on surface
Can open and close
Allow gas exchange
Allow water evaporation
- Alternation of Generations
-> 2 multicellular life stages
Haploid gametophyte- produces gametes by mitosis
Diploid sporophyte- produces spores by meiosis
- Multicellular, Dependent Embryo
2n embryo retained within tissue of female gametophyte. Nutrients transferred from parent.
- Walled Spores
Produced in Sporangia
Sporangia: Multicellular organs that produce spores
Sporocytes: Diploid cells, undergo meiosis-> haploid spores
Spores: Haploid reproductive cells
Spore wall contains sporopollenin
Resistant to harsh conditions
- Multicellular Gametangia
Gametangia: Multicellular gamete-producing organs- 2 types
Archegonia: Produce eggs, site of fertilization
Antheridia: Produce and release sperm
- Apical Meristems
Plants don’t move, do elongate
Apical meristems: Localized regions of cell division at tips of roots and shoots
Cells differentiate from apical meristems
- Cuticle
Waxy covering over all above-ground parts
Prevents desiccation
Provides some protection from microbes
Does not allow for gas exchange
- Stomata (singular= stoma)
Tiny openings on surface
Can open and close
Allow gas exchange
Allow water evaporation
Nonvascular Plants
Basal plants
Bryophytes- mosses and relatives
Lack specialized vascular systems
Paraphyletic
Vascular Plants
Includes both seedless and seed plants
Basal lineage: Seedless vascular plants
-Ferns and related plants
Paraphyletic
Seed Plants
Seed: Embryo with supply of nutrients within protective coat
Majority of extant plant species, best adapted for life on land.
Two types: Gymnosperms and angiosperms
Gymnosperms
“Naked seed”
Seeds not enclosed in a chamber
Example: Conifers
Angiosperms
“Container seed”
Flowering plants
Seeds enclosed in fruit
Most dominant type of plant
Nonvascular plants characteristics
Basal land plants
Small, herbaceous (non-woody)
Mosses (Bryophyta)
(And related plants)
No specialized transport tissue
Rely on diffusion, osmosis
-> typically small
Require moist environment for water and reproduction
Bryophyte Life Cycle
Define:
Gametophyte
Antheridium
Archegonium
Sporophyte
Sporangium
Gametophyte: Gamete-forming plant (haploid)
Antheridium: Sperm-producing structure
Archegonium: Egg-producing structure
Sporophyte: Spore-forming plant (diploid)
Sporangium: Spore-producing structure
Moss Life Cycle
Spores are dispersed due to meiosis by sporangium.
Spores are either male or female gametophyte (n).
If male, becomes antheridia. If female, becomes archegonia.
Release sperm and egg.
Fertilization occurs within archegonium.
Forms diploid zygote.
Divisions and becomes embryo.
Growth and becomes young sporophyte.
Matures into mature sporophytes.
Goes through meiosis and forms haploid spores.
Importance of Mosses
Extremely common
Can colonize bare, sandy soil
-> help retain N in soil
Sometimes harbor N-fixing bacteria
Peat: Partially decayed organic matter
Moss is important component
Important fuel source
Important C reservoir
Derived Traits of Vascular Plants
- Sporophyte dominant- lager, independent
- Transport in vascular tissue- have lignin
Lignin: Polymer in cell walls of water-conducting cells
Enables tall growth
-> Outcompete shorter plants for light, better spore dispersal - Roots: Organs that absorb water and nutrients from soil, anchor plants. -> allow for taller growth
- Leaves: Primary photosynthetic organs, increase surface area
- Sporophylls: Modified leaves with sporangia
Very diverse
Classification of “Seedless Vascular Plants”
Paraphyletic
Ferns (monilophytes) and related plants
