As the interfertility of oranges and other citrus has produced numerous hybrids, bud unions, and cultivars, their taxonomy is fairly controversial, confusing or inconsistent. The fruit of any citrus tree is considered a hesperidium (a kind of modified berry) because it has numerous seeds, is fleshy and soft, derives
In the early 19th century, Jean-Baptiste Lamarck proposed his theory of the transmutation of species, the first fully formed theory of evolution. In 1858, Charles Darwin and Alfred Russel Wallace published a new evolutionary theory that was explained in detail in Darwin’s On the Origin of Species (1859).
This results in an oval ring around each magnetic pole where auroras occur. The north pole aurora is called the aurora borealis and the aurora at the south pole is called the aurora australis. Depending on the level of recent solar activity, there may or may not be visible auroral activity all the way around the ring.