Epinasty is a botanical term that refers to the abnormal growth of plant parts, such as leaves or petals, in a downward direction. The spelling of the word can be explained using the International Phonetic Alphabet (IPA), which represents the sounds of language. The first syllable, "e-" is pronounced as "ɛ", like the short "e" in "bed". The second syllable, "-pi-" is pronounced as "pɪ", with a short "i" sound like the "i" in "hit". The final syllable, "-nasty", is pronounced as "næsti", with the stress placed on the first syllable.
Epinasty is a botanical term referring to a phenomenon observed in plants where the upper surface of a leaf becomes curved or curled inward, causing the leaf to appear concave or downturned. This curvature is a result of differential growth between the upper and lower surfaces of the leaf, with the upper side growing at a faster rate or experiencing greater expansion.
Epinasty is commonly seen as a response to certain environmental cues or stimuli, such as changes in light intensity, temperature, humidity, or exposure to certain chemicals. It can also be induced by certain hormonal imbalances or interactions, specifically involving the plant hormone ethylene.
The exact mechanism underlying epinasty is not fully understood, but it is believed to involve differential rates of cell expansion and cell division on each side of the leaf. The increased growth on the upper side causes the leaf to curl or bend downward, positioning the stomata (small openings on the leaf surface) on the underside for protection from excessive moisture loss or to optimize gas exchange.
Epinasty can have both positive and negative effects on the plant. In certain cases, it aids in protecting the leaves from harsh environmental conditions, reducing water loss, or redirecting light to improve photosynthesis. However, excessive or prolonged epinasty can lead to diminished growth, reduced productivity, or even damage to the leaf tissues.
In botany, noting a condition of more vigorous growth on the upper than on the under surface, causing a downward curvature.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "epinasty" is derived from the Greek roots "epi", which means "upon" or "above", and "nastos", meaning "spread out". The combination of these roots gives the word "epinasty" its meaning of a growth or movement of plant parts, such as leaves or petals, that are bent or curved upward or away from the axis of the plant.