Physiological Ecology of Plants

Terms:
phreatophytes, succulents, perennials, light compensation point, light saturation point, light attenuation, epiphytes, acclimitization, abcisic acid (ABA), xerophyte, mesophyte, halophyte, hydrophyte

abcisic acid (ABA):  Hormone produced by plants that helps acclimate them to colder temperatures as seasons change in the fall.  The hormone is produced under control of changing photoperiod and not temperature.  Causes cell walls to be more permeable to water to help prevent freezing.

acclimitization:  A reversible adaptation to seasonal changes in temperature or other factors. In plants, acclimitization allows the killing temperature to be lowered below freezing with production of abcisic acid during acclimitization.

epiphytes:  Plants that live on other plants without taking nutrients from them, such as a fern growing on a tree.

halophyte: A plant adapted to survive in soils with high concentration of salts or other minerals. It may have a high concentration of substances in its tissue to promote osmosis.

hydrophyte:  A plant adapted to live in water.  It may have stomata on the top of the leave for gas exchange when floating and lacuna or air pockets in the leaf for buoyancy. 

light compensation point: The point at which the amount of light energy available for photosynthesis produces just enough energy to equal the amount used to maintain cellular activities.

light saturation point: The point at which maximum photosynthetic rate is reached no matter how much more light is available.

light attenuation: The absorption and reflection of light as it passes through vegetation (e.g., a forest canopy to the ground) or water (with depth).  

mesophyte:  A plant adapted to moderate levels of moisture in its morphology and physiology..

perennial: A plant that flowers two or more years.

phreatophyte:  A plant with a deep tap root that allows it to gain a continuous source of water from the water table.

succulent: A plant that stores water in its tissues.

xerophyte: A plant adapted to dry, hot regions through its morphology and physiology.