Lecture 23- Plant Adaptations II Flashcards
Water movement in plants relies on?
- Cohesion of water
- Capillary action in xylem tubes
- Evapotranspiration from leaves
What is a cavitation?
Air embolism that breaks continuity of the water column
As the ice melts, the pressure is reduced to ____
Zero
____ allows for continuity of the water column to be restored
Torus reopening
What are some benefits of evergreen leaves?
- Leaf longevity may provide an advantage over deciduous leaves in areas with short growing seasons
- Evergreens benefit from long term return from investment > 1 year (lower cost than making new leaves annually)
- Beneficial in nutrient poor soils (less nutrients required)
- Start photosynthesis as soon as the temperature permits
- Provide more protection from drought, freezing, herbivory
Some plants form ____ leaves in late summer
Semi-evergreen leaves (becomes storage organs for sugar, carbs)
In aspen, up to ____ of total photosynthesis is in the bark
15%
Winter bark photosynthesis allows for ____
Competition with conifers
Photosynthetic bark offsets ____
Offsets continuous respiratory loss of carbohydrates in woody plants during winter
What are some disadvantages to evergreen leaves?
- High lignin buildup in needles (increased cost for maintenance)
- Coldest areas with highest cost of needle maintenance
- Cost of making defense compounds
- Lower photosynthetic rate per leaf area
What are some examples of mechanical damage?
- Heavy snow buildup
- Snow abrasion
- Browsing by mammals
What are some examples of adaptations to heavy snow buildup?
- Spiral and conical growth forms
- Branch adaptations (short, flexible, and downward pointing)
- Narrow needles do not accumulate much snow
What is snow abrasion?
- Cold and dry = sharp snow particles
- Wind blows snow particles into plant tissues
- Usually paired with desiccation
What are some adaptations to snow abrasion?
- Trees grow multiple stems (reduce wind velocity)
- Utilization of microtopography
- Cushions, clonal growth
Woody vegetation is targeted by?
- Ungulates
- Hares
- Rodents (porcupines, squirrels, mice)
