Nothofagus

Nothofagus, also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere, found across southern South America and east and southeast Australia, New Zealand, New Guinea, and New Caledonia. The species are ecological dominants in many temperate forests in these regions. Some species are reportedly naturalised in Germany and Great Britain. The genus has a rich fossil record of leaves, cupules, and pollen, with fossils extending into the late Cretaceous period and occurring in Australia, New Zealand, Antarctica, and South America.

Description

The leaves are toothed or entire, evergreen or deciduous. The fruit is a small, flattened or triangular nut, borne in cupules containing one to seven nuts.
Many individual trees are extremely old, and at one time, some populations were thought to be unable to reproduce in present-day conditions where they were growing, except by suckering, being remnant forest from a cooler time. Sexual reproduction has since been shown to be possible.

Taxonomy

The genus Nothofagus was first formally described in 1850 by Carl Ludwig Blume who published the description in his book Museum botanicum Lugduno-Batavum, sive, Stirpium exoticarum novarum vel minus cognitarum ex vivis aut siccis brevis expositio et descriptio. Nothofagus means "false beech", which Blume chose to indicate that Nothofagus species were different from beeches in the Northern Hemisphere.
In the past, they were included in the family Fagaceae, but genetic tests revealed them to be genetically distinct, and they are now included in their own family, Nothofagaceae. This taxonomy was introduced in 1962 by Russian botanist and palynologist Ludmila Andreyevna Kuprianova, who used pollen traits to erect Nothofagaceae. A study in 1999 found that the pollen exine ultrastructure of Nothofagus differs from that of Fagaceae genera by its thickness, type of aperture, and ornamentation, reinforcing the placement of Nothofagus in its own family.

Species list

The following is a list of species, hybrids and varieties accepted by the Plants of the World Online as of April 2023:

Nothofagus aequilateralis Steenis
Nothofagus alessandrii Espinosa
Nothofagus alpina Oerst.
Nothofagus antarctica Oerst.
Nothofagus balansae Steenis
Nothofagus baumanniae Steenis
Nothofagus betuloides Oerst.
Nothofagus brassii Steenis
Nothofagus carrii Steenis
Nothofagus cliffortioides Oerst.
Nothofagus codonandra Oerst.
Nothofagus crenata Steenis
Nothofagus cunninghamii Oerst.
Nothofagus discoidea Steenis
Nothofagus dombeyi Oerst.
Nothofagus flaviramea Steenis
Nothofagus fusca Oerst.
Nothofagus glauca Krasser
Nothofagus grandis Steenis
Nothofagus gunnii Oerst.
Nothofagus macrocarpa F.M.Vázquez & R.A.Rodr.
Nothofagus menziesii Oerst.
Nothofagus moorei Krasser
Nothofagus nitida Krasser
Nothofagus nuda Steenis
Nothofagus obliqua Oerst.
Nothofagus perryi Steenis
Nothofagus pseudoresinosa Steenis
Nothofagus pullei Steenis
Nothofagus pumilio Krasser
Nothofagus resinosa Steenis
Nothofagus rubra Steenis
Nothofagus rutila Ravenna
Nothofagus solandri Oerst.
Nothofagus starkenborghiorum Steenis
Nothofagus stylosa Steenis
Nothofagus truncata Cockayne
Nothofagus womersleyi Steenis
Nothofagus × apiculata Cockayne
Nothofagus × blairii Kirk
Nothofagus × dodecaphleps Mike L.Grant & E.J.Clement
Nothofagus × eugenananus Gilland.
Nothofagus × leoni Espinosa
Nothofagus × solfusca Allan
Subgenera

Four subgenera are recognized, based on morphology and DNA analysis:

Subgenus Fuscospora, six species in New Zealand, Tasmania, and southern South America.
Subgenus Lophozonia, seven species in New Zealand, Australia, and southern South America.
Subgenus Nothofagus, five species in southern South America.
Subgenus Brassospora, 20 accepted species in New Guinea and New Caledonia.

Further reinforcing the four-clade model is their reproductive isolation from each other—naturally occurring and cultivated Nothofagus have been recorded only between species of the same subgenus. Fuscopora, Lophozonia, and the Nothofagus subgenus often grow side-by-side, with plenty of opportunities to hybridize. Endemic to Papua New Guinea and New Caledonia, Brossospora does not occur in areas with other subgenera.
In 2013, Peter Brian Heenan and Rob D. Smissen proposed splitting the genus into four, turning the four recognized subgenera into the new genera Fuscospora, Lophozonia and Trisyngyne, with the five South American species of subgenus Nothofagus remaining in genus Nothofagus. The two authors posited that the four clades have evolutionary equivalence with other Fagales genera, and that the morphological and molecular differences are pronounced enough to raise the subgenera a rank. The proposed new genera are not accepted at the World Checklist of Selected Plant Families.

Extinct species

The following additional species are listed as extinct:

†Nothofagus australis
†Nothofagus balfourensis
†Nothofagus beardmorensis
†Nothofagus bulbosa
†Nothofagus cethanica
†Nothofagus cooksoniae
†Nothofagus crenulata
†Nothofagus cretacea
†Nothofagus densinervosa
†Nothofagus elongata
†Nothofagus glandularis
†Nothofagus glaucifolia
†Nothofagus lanceolata
†Nothofagus lobata
†Nothofagus magelhaenica
†Nothofagus magellanica
†Nothofagus maideni
†Nothofagus microphylla
†Nothofagus mucronata
†Nothofagus muelleri
†Nothofagus novae-zealandiae
†Nothofagus pachyphylla
†Nothofagus palustris
†Nothofagus peduncularis
†Nothofagus robusta
†Nothofagus serrata
†Nothofagus serrulata
†Nothofagus simplicidens
†Nothofagus smithtonensis
†Nothofagus tasmanica
†Nothofagus ulmifolia
†Nothofagus variabilis
†''Nothofagus zastawniakiae''
Evolutionary history

Nothofagus first appeared in Antarctica during the early Campanian stage of the Late Cretaceous. During the Campanian Nothofagus diversified and became dominant within Antarctic ecosystems, with the appearance of all four modern subgenera by the end of the stage. Nothofagus shows a progressive decline in the Antarctic pollen record through the Maastrichtian, before substantially recovering after the Cretaceous-Paleogene boundary. Nothofagus persisted in Antarctica deep into the Cenozoic, despite the increasingly inhospitable conditions, with the final records from the late Neogene, around 15-5 million years old, which were small tundra-adapted prostrate shrubs, similar to Salix arctica.
Nothofagus first appeared in southern South America during the late Campanian. During the Paleocene and Eocene they were mostly restricted to southern Patagonia, before reaching a peak abundance during the Miocene. Their distribution contracted westwards during the late Miocene due to the aridification of Patagonia.
Although the genus now mostly occurs in cool, isolated, high-altitude environments at temperate and tropical latitudes, the fossil record shows that it survived in climates that appear to be much warmer than those that Nothofagus now occupies.
File:Nothofagus range including New Caledonia.jpg|thumb|The Nothofagus plant genus illustrates the distribution on fragments of the old supercontinent Gondwana: Australia, New Guinea, New Zealand, New Caledonia, Argentina, and Chile.

Distribution

The pattern of distribution around the southern Pacific Rim suggests the dissemination of the genus dates to the time when Antarctica, Australia, and South America were connected in a common land-mass or supercontinent referred to as Gondwana. More recent studies suggest that the Antarctic land bridge likely played a major role in the dispersal of the genus between these continents. However, genetic evidence using molecular dating methods has been used to argue that the species in New Zealand and New Caledonia evolved from species that arrived in these landmasses by dispersal across oceans. Uncertainty exists in molecular dates and controversy rages as to whether the distribution of Nothofagus derives from the break-up of Gondwana, or if long-distance dispersal has occurred across oceans. In South America, the northern limit of the genus can be construed as La Campana National Park and the Vizcachas Mountains in the central part of Chile.

Ecology

Nothofagus species are used as food plants by the larvae of hepialid moths of the genus Aenetus, including A. eximia and A. virescens. Zelopsis nothofagi is a leaf hopper, endemic to New Zealand, which is found on Nothofagus.
Cyttaria is genus of ascomycete fungi found on or associated with Nothofagus in Australia and South America. Misodendrum are specialist parasitic plants found on various species of Nothofagus in South America. Additionally, the beetle, Brachysternus prasinus, has been known to live in Nothofagus in Chile and in parts of Argentina. The geographic range of B. prasinus is highly dependent on the availability and distribution of Nothofagus on which B. prasinus is believed to feed. B. prasinus have been observed in the Nothofagus forests near the cities of Coquimbo and Llanquihue in Chile as well as the areas of Neuquén and Chubut in Western Argentina.
The species of subgenus Brassospora are evergreen, and distributed in the tropics of New Guinea, New Britain, and New Caledonia. In New Guinea and New Britain Nothofagus is characteristic of lower montane rain forests between elevation, occurring infrequently at elevations as low as, and in upper montane forests between elevation. Nothofagus is most commonly found above the Castanopsis-Lithocarpus zone in the lower montane forests, and below the conifer-dominated upper montane forests. Nothofagus grows in mixed stands with trees of other species or in pure stands, particularly on ridge crests and upper slopes. The Central Range has the greatest diversity of species, with fewer species distributed among the mountains of western and northern New Guinea, New Britain, and Goodenough and Normanby islands.
The New Caledonian species are endemic to the main island, most commonly on soils derived from ultramafic rocks between elevation. They occur in isolated stands, forming a low or stunted and irregular and fairly open canopy. The conifers Agathis and Araucaria are sometimes present as emergents, rising above the Nothofagus canopy.