Hormones

Many people are more familiar with hormones being produced in animals than in plants. For example, insulin is produced in the pancreas and is involved in the metabolism of sugar. The thyroid gland produces the iodine-containing hormone called thyroxine. The adrenal glands produce adrenalin. With regard to animals, hormones are defined in part as being produced by ductless glands. With regard to plants, hormones are defined as substances produced in minute amounts at one site that have a physiological effect at another site.