auxins
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:

  • auxins — A group of plant growth substances (often called phytohormones or plant hormones), the most common example being indole acetic acid (IAA), responsible for raising the pH around cells, making the cell wall less rigid and allowing elongation …   Dictionary of molecular biology

  • auxins — n. plant hormone …   English contemporary dictionary

  • Auxin — Auxins are a class of plant growth substance (often called phytohormone or plant hormone). Auxins play an essential role in coordination of many growth and behavioral processes in the plant life cycle.OverviewAuxins derive their name from the… …   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

  • 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

  • Ethylene — Ethylene …   Wikipedia

  • angiosperm — /an jee euh sperrm /, n. Bot. a plant having its seeds enclosed in an ovary; a flowering plant. Cf. gymnosperm. [ANGIO + SPERM] * * * ▪ plant Introduction       any member of the more than 300,000 species of flowering plants (division Anthophyta) …   Universalium

  • auxin — auxinic, adj. /awk sin/, n. Biochem. a class of substances that in minute amounts regulate or modify the growth of plants, esp. root formation, bud growth, and fruit and leaf drop. [1930 35; AUX + IN2] * * * Any of a group of hormones that… …   Universalium

  • 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

  • Phototropism — is directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth and response to a light stimulus. Phototropism is most often observed in plants, but can also occur in… …   Wikipedia

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