Five known classes of hormones control plant growth and development
Auxin – promotes fruit growth
Cytokinins – stimulate cell division
Gibberellins – stimulate growth in leaves and stems
Abscisic Acid – slows plant growth
Ethylene – inhibits root growth
Phototropism –bends shoot towards light; enhances photosynthesis
Gravitropism – uses specialized plastids
Roots display positive gravitropism
(grows down towards the earth) and the shoot displays negative gravitropism
(grows up out of the earth)
Developmental response to mechanical stimulation
Example: thicker stemmed plants are found in locations where the winds are strong
Turgor movements are relatively rapid, reversible plant responses
Biological clocks control circadian rhythms in plants and other eukaryotes
Photoperiodism synchronizes many plant responses to changes of season
Phytochrome functions as a photoreceptor in many plant responses to light and photoperiod
Control systems enable plants to cope with environmental stress
The study of plants began when early humans began to distinguish edible plants from poisonous ones.
Then began to make things from wood and other plant products.
Today scientists aim for increasing crop productivity, but the fun of discovery is what motivates most plant scientists.
Plant biology, one of the oldest branches of science, is driven by curiosity and need – curiosity about how plants work and a need to feed, clothe, and house an increasing human population. Plant biology is in the midst of a renaissance, in which new methods, coupled with clever choices of experimental organisms, have catalyzed a research explosion.