Hormone Hor"mone (h[^o]r"m[=o]n), n. [From Gr. "orma`ein to excite.] 1. (Physiological Chem.) A chemical substance formed in one organ and carried in the circulation to another organ on which it exerts a specific effect on cells at a distance from the producing cells; thus, pituitary hormones produced in the brain may have effects on cells in distant parts of the body.. [Webster 1913 Suppl. +PJC]

2. (Physiological Chem.) a chemical substance, whether natural or synthetic, that functions like a hormone in a living organism. Thus, synthetic steroid hormones may be more effective than their natural counterparts. [PJC]

3. (Bot.) A substance that controls growth rate or differentiation in plants; also called {phytohormone}. The most well-known are the {auxins} that stimulate growth at the growing tips of plants, and control root formation and the dropping of leaves; and the {gibberellins}, which are used in agriculture to promote plant growth. [PJC]

The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • gibberellins — A class of plant growth hormones (auxins) of which over 60 are known; these were first isolated in 1938 from cultures of Gibberella fujikuroi, the fungus causing Bakanese disease in rice. Also found in higher plants; diterpenoid acids available… …   Medical dictionary

  • gibberellins — A class of plant growth regulators which are active in the elongation, enhancement of flower, fruit and leaf size, germination, vernalization and other physiological processes …   Glossary of Biotechnology

  • Gibberellin — Gibberellins (GAs) are plant hormones that regulate growth and influence various developmental processes, including stem elongation , germination, dormancy, flowering, sex expression, enzyme induction and leaf and fruit senescence.… …   Wikipedia

  • hormone — hormonal, hormonic /hawr mon ik, moh nik/, adj. /hawr mohn/, n. 1. Biochem. any of various internally secreted compounds, as insulin or thyroxine, formed in endocrine glands, that affect the functions of specifically receptive organs or tissues… …   Universalium

  • malformation — /mal fawr may sheuhn, feuhr /, n. faulty or anomalous formation or structure, esp. in a living body: malformation of the teeth. [1790 1800; MAL + FORMATION] * * * ▪ biology Introduction       in biology, irregular or abnormal structural… …   Universalium

  • plant development — Introduction       a multiphasic process in which two distinct forms succeed each other in alternating generations. One form, created by the union of sexual cells (gametes (gamete)), contains two sets of similar chromosomes (diploid). At sexual… …   Universalium

  • Plant hormone — Plant hormones (also known as phytohormones) are chemicals that regulate plant growth. Plant hormones are signal molecules produced within the plant, and occur in extremely low concentrations. Hormones regulate cellular processes in targeted… …   Wikipedia

  • Lew Mander — Infobox Scientist image width = 150px name = Professor Lew Mander birth date = Birth date and age|1939|9|8|mf=y birth place = Auckland, New Zealand death date = death place = residence = Canberra, Australia citizenship = field = Organic Chemist… …   Wikipedia

  • horticulture — horticultural, adj. horticulturist, n. /hawr ti kul cheuhr/, n. 1. the cultivation of a garden, orchard, or nursery; the cultivation of flowers, fruits, vegetables, or ornamental plants. 2. the science and art of cultivating such plants. [1670… …   Universalium

  • Epidermis (botany) — Cross section of a flax plant stem: 1. Pith, 2. Protoxylem, 3. Xylem I, 4. Phloem I, 5. Sclerenchyma (bast fibre), 6. Cortex, 7. Epidermis The epidermis is a single layered group of cells that covers plants …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”