epinasty

American  

[ep-uh-nas-tee] / ˈɛp əˌnæs ti /

noun

Botany.

1. (especially of leaves) increased growth on the upper surface of an organ or part, causing it to bend downward.

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epinasty British  

/ ˈɛpɪˌnæstɪ /

noun

1. increased growth of the upper surface of a plant part, such as a leaf, resulting in a downward bending of the part Compare hyponasty

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Other Word Forms

• epinastic
  adjective

Etymology

Origin of epinasty

1875–80; epi- + Greek nast ( ós ) pressed close + -y ³

Example Sentences

The young leaves of Cannabis sativa sink at night between 30o and 40o beneath the horizon; and Kraus attributes this to epinasty in conjunction with the absorption of water.

From The Power of Movement in Plants by Darwin, Charles

De Vries has shown* that the more or less horizontal position of leaves is in most cases influenced by epinasty, by their own weight, and by apogeotropism.

From The Power of Movement in Plants by Darwin, Charles

On the other hand, from observing the effects of tying a shoot downwards, so that the rectangle faced upwards, we are led to believe that the curvature is partly due to epinasty.

From The Power of Movement in Plants by Darwin, Charles

As this latter movement occurred in complete darkness, and with peduncles arising from upright and from dependent branches, it cannot be due to apheliotropism or to epinasty, but must be attributed to geotropism.

From The Power of Movement in Plants by Darwin, Charles

As the arching occurred in whatever position the seeds were placed, it is no doubt due to temporarily increased growth of the nature of epinasty or hyponasty along one side of the part.

From The Power of Movement in Plants by Darwin, Charles