BIOA01H3 Lecture Notes - Lecture 12: Utricularia, Victoria Amazonica, Vallisneria

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13 Apr 2012
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LECTURE TWELVE
Plant life on the edge
Plants have adapted to a huge range of extreme habitats/environments/climates
Frost
Heat/drought
Perpetual inundation
Salty habitats
Toxic solids heavy metals
Extreme nutrient limitation
Low light
Perpetual inundation
An overabundance of fresh water can cause other things to become limiting for example carbon
dioxide as carbon dioxide concentration decreases as well as oxygen. How to access these gases.
Limitations in a freshwater environment; [CO2] , and [O2]for photosynthesis is lower in water
than in air
Light decreases as you go lower down in water
Nutrient levels are lower underwater, compared to in soil
In running water; the current can be very strong; plants need to adapt to this
Types of aquatic plants
True hydrophytes ;submerged plants
Floating [inside the water] vs emergent leaves [in the open with a little water]
Free roots vs. no roots
True hydrophytes [submerged plants]
Spend entire life cycle underwater: water is not a limiting resource
Dissected narrow leaves
Greatest number of adaptations:
Poorly developed xylem; no need for water carrying structures
Almost no mechanical strengthening; water supports the weight; no collenchyma or
sclerenchyma
Maximum surface to volume ratio
The minimal O2 and CO2 can get in quickly
Thin cuticles, no stomata [since no gas exchange]
Running out of water is not a problem
Adapted intercellular air space
To keep them well positioned in water
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