Nut (fruit) usage of the term is less restrictive, and many nuts (in the culinary sense), such as almonds, pecans, pistachios, walnuts, and Brazil nuts, are not nuts in a botanical sense. Common usage of the term often refers to any hard-walled, edible kernel as a nut. A nut in botany is a simple dry fruit in which the ovary wall becomes increasingly hard as it matures, and where the seed remains unattached or free within the ovary wall. Most nuts come from the pistils with "inferior" ovaries (see flower) and all are "indehiscent" (not opening at maturity). True nuts are produced,
Australian green tree frog by the preservative and appeared blue. The color of the frog is caused by blue and green pigments covered in a yellow layer; the preservative destroyed the yellow layer and left the frog with a blue appearance. The specific epithet, "caerulea", which is Latin for blue, has remained. This frog is sometimes referred to as "Pelodryas caerulea" in the scientific literature. In Australia, the frog is also known more simply as the "green tree frog", but that name is often given to the most common green arboreal species in a region, such as the American green tree frog ("Hyla cinerea").