Estivazione

Estivazione, or estivation in English, is primarily a state of dormancy that some animals enter during hot or dry seasons to conserve water and energy. During estivation, metabolic rate, heart rate, and ventilation slow; activity is reduced, and individuals may survive in burrows, mud cocoons, or shaded refuges for extended periods until conditions improve. The phenomenon is widespread among tropical and desert species, including amphibians, reptiles, and invertebrates. A well-documented example is the African bullfrog (Pyxicephalus adspersus), which seals itself in a mud cocoon during dry periods. Estivation is often compared to hibernation, which occurs in colder seasons, but it is triggered by heat and aridity rather than cold.

In botany, estivation refers not to dormancy but to the arrangement of floral organs within the bud, particularly the petals or sepals before the flower opens. This morphological feature helps distinguish species and is described by patterns such as imbricate (overlapping) and valvate (hinge-like) estivation, among others like contort and quincuncial. The term is used in floriculture, taxonomy, and anatomy to describe bud structure rather than a seasonal response.

The word estivation comes from Latin aestivatio, meaning summer or summering. Its usage spans zoology and botany, reflecting the different meanings of estivation across biological disciplines.