Auxins

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  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]