| A | B |
|---|
| plant hormone | chemical messenger in a plant |
| auxin | plant hormone that promotes plant growth |
| cytokinin | plant hormome that stimulates cell division |
| gibberellin | plant hormone that stimulates growth of stems |
| dormancy | period when a plant stops growing |
| abscisic acid | plant hormone that inhibits cell division in buds and vascular cambium |
| ethylene | plant hormone that stimulates fruit ripening and leaf drop |
| tropism | growth response that causes parts of a plant to grow toward or away from a stimulus |
| thigmotropism | plant growth in response to touch |
| phototropism | growth of a plant part toward or away from light |
| gravitropism | growth of a plant in response to gravit |
| halophyte | salt-tolerant plant |
| circadiam rhythm | rhythmic pattern of behavior (in an animal) or biological cycle (in plant) that follows an approximately 24-hour natural cycle |
| photoperiodism | plant response to cycles of light and darkness |
| short-day plant | plant that blooms when the dark period exceeds a critical length |
| long-day plant | plant that blooms when dark period is shorter than a critical length |
| day-neutral plant | plant that blooms when it reaches a certain stage of maturity, regarless of day length |
| phytochrome | pigmented plant protein that detects light |
