Pecan "fruit of the walnut". They noted the particularly thin shell and acorn-like shape of the fruit, indicating they were indeed referring to pecans. The Spaniards took the pecan into Europe, Asia, and Africa beginning in the 16th century. In 1792, William Bartram reported in his botanical book, "Travels", a nut tree, "Juglans exalata" that some botanists today argue was the American pecan tree, but others argue was hickory, "Carya ovata". Pecan trees are native to the United States, and writing about the pecan tree goes back to the nation's founders. Thomas Jefferson planted pecan trees, "C. illinoinensis" (Illinois nuts), in
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").