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.

---

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

---

Other Word Forms

• epinastic
  adjective

Etymology

Origin of epinasty

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

Example Sentences

See Examples For:

epinasty

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

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

A young cotyledon or leaf after bursting free is brought down into its proper position, as already remarked, by epinasty, which, according to De Vries, long continues to act on the midribs and petioles.

From The Power of Movement in Plants by Darwin, Charles

Therefore this case seems very different from that of ordinary sleep, and probably comes under the head of epinasty, as is the case with the leaves of this plant according to Kraus.

From The Power of Movement in Plants by Darwin, Charles

Many organs bend downwards through epinasty or apheliotropism or from their own weight; but we have met with very few cases of a downward movement in sub-aërial organs due to geotropism.

From The Power of Movement in Plants by Darwin, Charles