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]

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Any of a group of hormones that regulate plant growth, particularly by stimulating cell elongation in stems and inhibiting it in roots.

Auxins influence the growth of stems toward light (phototropism) and against the force of gravity (geotropism). Auxins also play a role in cell division and differentiation, fruit development, the formation of roots from cuttings, the inhibition of lateral branching, and leaf fall. The most important naturally occurring auxin is beta-indolylacetic acid.

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▪ biochemistry

      any of a group of hormones that regulate plant growth, particularly by stimulating cell elongation in stems and inhibiting it in roots. For example, auxins influence the growth of stems toward light (phototropism) and against the force of gravity (geotropism). Auxins also play a role in cell division and differentiation, in fruit development, in the formation of roots from cuttings, in the inhibition of lateral branching (apical dominance), and in leaf fall (abscission). The most important naturally occurring auxin is beta-indolylacetic acid.

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