paratonic

from The Century Dictionary.

• Due to the influence of an external stimulus, such as light, gravity, or humidity: thus used by Strassburger in the phrase paratonic movements, opposed by him to autonomic movements.
• Arresting or retarding plant movement or growth: a term proposed by Sachs, in 1865, to characterize the variations in intensity of light which produce the movements of waking and sleeping (nyctitropism) in plants, in contradistinction to heliotropism.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective medicine Of or relating to paratonia.