The northern beeches, of which Fagus sylvatica is the type, form a very homogeneous group of invariably deciduous trees with broad leaves; they are confined to the temperate latitudes of the northern hemisphere. The beeches of the southern hemisphere are mainly evergreen and are a larger, more varied group, with almost forty species (against ten in Fagus). Of these nine are natives of temperate S. America (Chile and bordering parts of Argentina); three occur in Tasmania and Australia; five in New Zealand. It has quite recently been discovered that southern beeches dominate in some of the remote mountain forests of New Guinea, and sixteen species were described from this region in 1952-3. There are also five species in New Caledonia, two of which were described by Baillon in 1874, but in a new genus – Trisyngyne – which he believed to belong to the Euphorbiaceae.
As remarked above, the southern beeches are mainly evergreen. But seven are deciduous, all of them from Chile and Argentina except the Tasmanian N. gunnii. It is interesting that these deciduous species resemble the northern beeches in having the leaves plicately folded in the bud, i.e., concertina-wise; in the evergreen species they are folded along the midrib. The leading characters of Nothofagus are: male flowers solitary or in pairs or threes, sessile or shortly stalked (in Fagus they are borne in globose, many-flowered, stalked inflorescences); female flowers usually three in each involucre (two in Fagus), normally each flower producing a nutlet, of which the two outer ones are three-winged or three-angled and the middle one flattened; styles short, not elongated as in Fagus. The valves of the involucre are essentially the same as in Fagus but are often obviously composed of several scales (lamellae) and the processes are more varied in form. Sometimes, too, they are much narrower than the nutlets and do not fully enclose them.
The name Nothofagus means ‘false beech’ or ‘resembling the beech’; but Notofagus, meaning ‘southern beech’, would have been more appropriate, and it has even been suggested that Blume, who first published the name Nothofagus, inserted the letter ‘h’ inadvertently.
There is no monograph on the genus Nothofagus, but a valuable key, which includes the S. American and Australasian species, was published by C. G. G. J. Van Steenis as part of a study mainly devoted to the species recently discovered in New Guinea (Journ. Arn. Arb., Vol. 34 (1953), pp. 328-38).
All the southern beeches so far introduced are hardy or nearly so in the woodland gardens of mid-Sussex, with the exception of N. moorei, which thrives only in the mildest parts. The deciduous species now in cultivation should grow satisfactorily over most of the British Isles (though N. procera is tender in some forms). The hardiest evergreen species is N. betuloides. Unlike the common beech, the southern beeches are not suitable for calcareous soils. They are poor wind-resisters in this country, possibly because they grow too fast and make top-growth out of proportion to their root-system.