Nothofagus

Nothofagus is a genus of 43 species of trees and shrubs. They are commonly known as southern beeches. These plants are ecological dominants in many temperate forests. This means they are a major part of their environments. They are found throughout the Southern Hemisphere. You can find them in Chile and Argentina in South America. They also grow in Australia, New Zealand, New Guinea, and New Caledonia.

These plants show a wide variety of physical traits. Some species are evergreen, meaning their leaves stay green all year. Other species are deciduous, which means they lose their leaves seasonally. The leaves can be entire or have toothed edges. The fruit of the Nothofagus is a small nut. These nuts can be flattened or triangular in shape. Each nut grows inside a structure called a cupule. A single cupule can contain between one and seven nuts.

Scientists have studied the taxonomy, or classification, of these trees for a long time. Carl Ludwig Blume first formally described the genus in 1850. He published his work in the book Museum botanicum Lugduno-Batavum. The name Nothofagus translates to "false beech." Blume chose this name because the trees differ from beeches in the Northern Hemisphere. In the past, they were placed in the family Fagaceae. However, genetic tests showed they are genetically distinct. In 1962, the Russian botanist Ludmila Andreyevna Kuprianova used pollen traits to create the family Nothofagaceae.

The genus is divided into four subgenera based on DNA and morphology. Morphology refers to the physical form and structure of the plants. The four subgenera are Fuscospora, Lophozonia, Nothofagus, and Brassospora. Subgenus Brassospora contains 20 species and is found in New Guinea and New Caledonia. It is unique because it does not grow near the other subgenera. In 2013, researchers Peter Brian Heenan and Rob D. Smissen suggested a change. They proposed splitting the genus into four separate genera. They argued that the differences between the groups were large enough to justify this. However, the World Checklist of Selected Plant Families has not accepted this change.

The evolutionary history of Nothofagus is very deep. The genus first appeared in Antarctica during the Late Cretaceous period. This was during the Campanian stage, roughly 83.6 to 72.1 million years ago. During this time, Nothofagus became a dominant part of Antarctic ecosystems. Fossils of leaves, pollen, and cupules have been found in Antarctica and South America. Even as Antarctica became colder, Nothofagus persisted there for a long time. The final fossil records from the late Neogene show small, tundra-adapted shrubs. These shrubs were likely similar to the modern Arctic willow.

There is a scientific debate about how these trees spread across the globe. One theory is based on the supercontinent Gondwana. This was a massive landmass that once connected Antarctica, Australia, and South America. This theory suggests the trees moved across connected land. This process is known as vicariance. Other scientists argue for long-distance dispersal. They suggest the trees may have traveled across oceans to reach places like New Zealand. Genetic evidence using molecular dating is used to study these different possibilities.

Nothofagus forests support many different types of life. For example, the larvae of hepialid moths, such as Aenetus eximia, use these trees as food plants. In New Zealand, a leaf hopper called Zelopsis nothofagi lives on the trees. Some fungi, like the genus Cyttaria, are associated with Nothofagus in Australia and South America. In South America, specialist parasitic plants called Misodendrum grow on them. Even beetles rely on these forests. The beetle Brachysternus prasinus lives in Chile and Argentina. Its survival depends heavily on the presence of Nothofagus trees.