Gravitropisms

《英文msh詞典》Gravitropisms
[入口詞] Gravitropisms
[主題詞] Gravitropism
[英文釋義] The directional growth of organisms in response to gravity. In plants,the main root is positively gravitropic (growing downwards) and a main stem is negatively gravitropic (growing upwards),irrespective of the positions in which they are placed. Plant gravitropism is thought to be controlled by auxin (AUXINS),a plant growth substance. (From Concise Dictionary of Biology,1990)