Describe
The derived characteristics common to all land plants
- Eukaryotic
- Cellulose cell walls
- Develops from embryos
- Possesses chloroplasts, mitochondria
- Alternates generations
Define
Embryo
Diploid multicellular structure enclosed in maternal tissue
Algae (charophytes) don’t develop from embryos
Define
Sporopollenin
Layer of durable polymer in charophytes, prevents spores from drying out
What are the derived traits of plants?
- Alternation of generations
- Multicellular, dependent embryos
- Walled spores
- Multicellular gametangia
- Apical meristems
Describe the alternation of generations in plants
- The diploid sporophyte (mature plant) produces by meiosis haploid spores
- The spores do mitosis and become a haploid gametophyte
- The gametophyte does mitosis and produces gametes
- Fertilization occurs, a diploid zygote is produced and matures into a sporophyte
What are the dominant stages in ferns and moss?
Moss is haploid dominant, while ferns are diploid dominant
Describe
Walled spores
Spores covered by sporopollenin, produced in sporangium from meiosis of sporophytes
Describe
Multicellular gametangia
Organ in which gametes are produced, archegonia for eggs and antheridia for sperm
Describe
Apical meristems
Localized regions of cell division
Describe
Vascular plants
- Grade, united by their having a complex vascular tissue system
- Depend on water availability (swimming sperm)
- Formed of 2 clades, lycophytes (club mosses, etc…) and monilophytes (ferns, more diversified than lycophytes), both seedless vascular
Describe
Bryophytes
- First clade, composes of non-vascular plants
- Depend on water availability (swimming sperm)
- 3 phyla: liverworts, mosses, hornworts
- Very present in peatlands, ecosystems very important for environment, hold 20-30% of organic carbon despite being 3% of Earth surface
Describe
The third clade, following bryophytes and vascular plants
Vascular plants with seeds, composed of two clades:
* Gymnosperms: seeds not enclosed in chambers (conifers); heterosporous
* Angiosperms: seeds in chambers (90% of plants)
In what order did the 3 clades appear?
- Land plants (470 mya)
- Vascular plants (425 mya)
- Extant seed plants (305 mya)
Angiosperms (140 mya)
What are the two types of vascular tissue?
- Xylem: water and mineral conduction, contain tracheid, tube-shaped cell for upwards carry
- Phloem: distribution of sugars
Describe
Roots
Organs that absorb water and nutrients from the soil. They also anchor vascular plants
Describe
Leaves
Primary photosynthetic organ of vascular plants
* microphylls: small, spine-shaped leaves
* megaphylls: large, vascular leaves
