Plant hormones

• Auxins = maintain apical dominance, control cell elongation, prevent leaf fall, stimulate release of ethene
• Gibberellins = cause stem elongation (longer internodes), trigger germination (stimulate the production of enzymes that break down the food stores), delay ripening
• Ethene = causes fruit ripening and promotes leaf fall in deciduous trees
• ABA = maintains dormancy of seeds and buds and stimulates stomatal closing
• Experimental Evidence:

  When the tip of a plant is cut off (no auxin is produced) then lateral growth occurs.