auxotonic

from The Century Dictionary.

• Determined by growth: in botany, applied to those movements of plants which are the result of growth, in distinction from those of matured organs influenced by stimulation. See allassotonic.

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

• adjective botany Relating to plant movement classified by growth as opposed to mature reactions to exogenous stimuli in surrounding environment. Antonym: allassotonic
• adjective physiology Of or involving muscular contraction against resistance in which the length of the muscle changes and the tension differs due to an increasing load or difference in leverage. Antonym in regard to movement is isometric. Antonym in regard to tonus is isotonic. Tonic movements (auxo or iso) are either concentric (working muscle shortens) or eccentric (working muscle lengthens).