Indeterminate growth

This inflorescence of the terrestrial orchid Spathoglottis plicata shows indeterminate growth; note that the opening of flowers and production of fruits is proceeding upwards on the shoot.

In biology and especially botany, indeterminate growth refers to growth that is not terminated in contrast to determinate growth that stops once a genetically pre-determined structure has completely formed. Thus, a plant that grows and produces flowers and fruit until killed by frost or some other external factor is called indeterminate. For example, the term is applied to tomato varieties that grow in a rather gangly fashion, producing fruit throughout the growing season, and in contrast to a determinate tomato plant, which grows in a more bushy shape and is most productive for a single, larger harvest, then either tapers off with minimal new growth/fruit, or dies. In reference to an inflorescence (a shoot bearing flowers), an indeterminate type (such as a raceme) has the flowers developing and opening from the base towards the growing tip. The growth of the shoot is not impeded by the opening of the early flowers or development of fruits and its appearance is of growing and producing flowers indefinitely. In a determinate inflorescence, typically all of the flower buds are formed before the first ones begin to open, and all open more or less at the same time; or a terminal flower blooms first and stops elongation of the main axis.

Animals

In zoology, indeterminate growth refers to the condition where animals grow rapidly when young, and continue to grow after reaching adulthood although at a slower pace. It is common in reptiles, most fish, and many mollusks. The term also refers to the pattern of hair growth seen in humans and a few domestic breeds, but rare in other mammals, where hair continues to grow in length until it is cut.

See also

• Determinate cultivar