Lecture 4: Physical challenges for terrestrial plants
Autotrophs: An organism that assimilates energy either from sunlight or from inorganic
Plants in hot deserts reduce their heat loads by producing finely subdivided leaves with
a large ratio of edge of surface area. Some have no leaves (cacti)
o Photosynthetic bark on trunks & branches; can grow without incurring heat load
& water loss through leaves
o Tiny and thick stemmed leaflets that contain chlorophyll.
o Leaves are subdivided into leaflets that facilitate dissipation of heat.
o Grows to 15 m,200 yr, 5+ tonnes
o Extensive, shallow roots
o Accordion-pleated trunk
o Can absorb 800 L of water from one storm, use it gradually for growth.
Plants under stress environment:
Deciduous habit: dropping leaves during dry or cold seasons can reduce water stress
and tissue damage.
Leaves with more turbulencebetter cooling.
o When objects are smoothboundary layers