Plants Flashcards
What and how did land plants evolve?
- From charophycean algae
- Algae moved from water to soil because of spaciousness, unfiltered sunlight, CO2 abundance, mineral rich soil, and few herbivores and pathogens
Describe the haploidiplontic life cycle?
Gametophyte undergoes mitosis and then fertilization occurs. The sporophyte (2n) part of the cycle then occurs. The sporangia goes through meiosis, creating four spores (n). The cycle then repeats with one of these spores.
What are the three phyla of Bryophytes?
- Hepatophyta (liverworts)
- Anthocerophyta (hornworts)
- Bryophyta (mosses)
What are the characteristics of plants in Bryophytes?
- Usually no connective tissue/poorly developed
- Gametophyte dominant (gametophyte: leafy structure)
- Sporophyte is parasitic on gametophyte
- Need moist environment to allow sperm to travel to egg
- Diverse bryophytes are not monophyletic
- Liverworts and hornworts may be most reasonable models for what early plants were like
- Mosses are the bryophytes that are most closely related to vascular plants
Describe Cooksonia?
- Seedless vascular plant
- Oldest known vascular plant
What are Pteridophytes?
Seedless vascular plants
What are the four phyla of Pteridophytes (seedless vascular plants)?
- Whisk ferns: Psilotophyta
- Club mosses and quillworts: Lycophyta
- Horsetails and scouring rushes: Equisetophyta
- Ferns: Polypodiophyta
Describe Psilotophyta (whisk ferns)?
- Simplest of all living vascular plants
- Have enations: little bumps instead of leaves
Describe Lycophyta (club mosses and quillworts)?
-Sporangia clustered together in cones or strobili which protects them
Describe Equisetophyta (horsetails and scouring rushes)?
- Silica is in scouring rushes (sharp)
- Still remaining genus: equisetum
- Flourished in Carboniferous
- Treelike (over 50 ft. tall)
- Not large surface area in leaves
Describe Polypodiophyta (ferns)?
- All have megaphylls: fronds
- Produce spores (megaspores or microspores)
- Wind dispersed
- Conspicuous sporophyte and much smaller gametophyte are both photosynthetic
- The sporophyte is diploid but also makes spores that disperse to reproduce which are haploid
Describe megaphylls?
-3 analogous structures called leaves
Leaves on gametophytes of nonvascular plants
Enations: microphylls
Megaphylls
-True leaves (megaphylls) are present in all seed plants, ferns, and some equisetophytes
Describe the evolution of seed plants?
- Seed plants evolved from spore-bearing fern-like plants
- Whole genome duplication: all DNA coplies (how seeds came about)
What are the benefits of seeds?
- Protect the embryo
- Provide nourishment to the embryo
- Easily dispersed
- Introduces dormant phase in the life cycle
Describe Gymnosperms (they are a classification of evolution)?
- Naked seed
- No flowers or fruits
- Most trees or shrubs
- More advanced than seedless vascular
