Larix, the larches, is a genus of about 10 to 14 species of deciduous conifers in the family Pinaceae. Unlike most members of the pine family, larches shed their needles every autumn after a striking change to golden yellow, a defining and easily recognised trait of the genus. Trees reach up to 60 m tall in some species and produce open, sparse crowns with broadly horizontal branching. Young bark is smooth and silver-grey to grey-brown, becoming thick, scaly, and reddish-brown with age. The wood is resinous, dense, and noted for its natural decay resistance.
The needles of larches show a characteristic dimorphic arrangement: they are borne singly along the long shoots of new growth, but emerge in dense rosettes of roughly 20 to 50 needles on short, woody spur shoots. Female (seed) cones are typically erect, globose to ovoid, and take four to seven months to reach maturity; they may persist on the branches for several years after the seeds are released. Male cones are small and inconspicuous. Most species are tall, pyramidal trees with rapid early growth, flowering in spring and ripening cones in autumn.
The genus Larix was formally established by Philip Miller in 1754, and the name derives from Larix, the classical Roman word for the tree. Larix is the type genus of subfamily Laricoideae within Pinaceae. Modern treatments recognise roughly eleven accepted species plus at least one naturally-occurring hybrid, with three broad geographic clades: a North American group (including the tamarack and western larch), a northern Eurasian group (encompassing the European, Siberian, Dahurian, and Japanese larches), and a southern Asian, Sino-Himalayan group centred on the Qinghai-Tibetan Plateau. Recent molecular work suggests the deepest split is between the high-latitude circumboreal species and the southern Asian taxa.
Larches are quintessential trees of the cold north and high mountains. They are found across the temperate and cold zones of the Northern Hemisphere, from Alaska and Canada through Europe and northern Siberia to mountainous China and Japan. Larix gmelinii, the Dahurian larch, is the world's most northerly-growing tree, reaching about 75° N on the Taymyr Peninsula of Siberia. The genus is a pioneer of disturbed, cold, and infertile sites, intolerant of shade and atmospheric pollution but exceptionally cold-hardy, and its timber, resin, and ornamental autumn colour give it both economic and aesthetic importance.
Etymology
The genus name Larix is the classical Roman word for the larch tree, applied by Philip Miller when he formally described the genus in 1754. The English vernacular name "larch" is first attested in 1548 in the writings of the botanist William Turner. It was borrowed from German Lärche, which descends through Middle High German from a conjectured Old High German form, itself ultimately derived from the Latin Larix through contact with Gaulish-speaking populations in the Alps.
Distribution
Larches are essentially trees of cold-temperate and boreal latitudes and of high mountains, distributed across the Northern Hemisphere. In North America they occur in boreal Alaska and Canada, in the northern Appalachian Mountains, and in the North Cascades and Northern Rockies. The northern Eurasian group spans the Alps and Carpathians of Europe and stretches across boreal Russia to Japan and northeastern China, including the European larch as a montane Alpine species and the Siberian and Dahurian larches as the dominant trees of vast tracts of the Russian taiga. A separate Sino-Himalayan group occupies the Qinghai-Tibetan Plateau and adjacent areas of China, Tibet, Bhutan, India, and Nepal. Larix gmelinii reaches further north than any other tree species on Earth, growing to about 75° N on the Taymyr Peninsula. In Europe west of its natural Alpine range, only Larix decidua and the introduced Larix kaempferi are well established; in Switzerland, for example, the national flora records both species.
Ecology
Larches are typical pioneer trees of cold, exposed, and disturbed sites. They are extremely cold-hardy and shade-intolerant, colonising cleared ground rapidly but giving way to more shade-tolerant conifers in mature forest succession. They form mycorrhizal associations with several fungi, most notably the larch bolete (Suillus grevillei), which is essentially specific to the genus. Foliage supports specialist insects including the larvae of the larch pug moth, while the large larch bark beetle (Ips cembrae) is associated with the genus but is generally a less destructive pest than its spruce-feeding relatives.
Cultivation
Larches do best in open, airy positions on light, well-drained soils, and they tolerate acid and relatively infertile substrates. They are intolerant of shade and of significant atmospheric pollution, and they establish rapidly on cleared land as classic pioneer trees. In commercial European forestry the Dunkeld or hybrid larch (Larix × marschlinsii, the hybrid between L. decidua and L. kaempferi) is an important plantation tree, often outperforming either parent for vigour and disease tolerance. Several species are also valued horticulturally and as subjects for bonsai cultivation.
Propagation
Larches are usually raised from seed. Seed requires roughly a month of cold stratification before sowing in late winter, and remains viable for about three years under good storage. Seedlings benefit from light shade in their first season before being moved to full sun, after which they grow rapidly.
Conservation
At genus level larches are not generally considered globally threatened, but they face significant disease pressures. Several species are susceptible to fungal canker diseases and to the oomycete pathogen Phytophthora ramorum, which has caused major mortality of Japanese larch plantations in parts of Britain. No Larix species are currently listed in the Global Invasive Species Database.
Cultural & Practical Uses
Larch timber has been important to humans wherever the genus grows. The wood is dense, resinous, and naturally decay-resistant, and is traditionally used for boatbuilding and yachts, exterior cladding, interior panelling, railway sleepers, and general construction. Larches also yield a range of valuable extractives: rosin and turpentine from the resin, the carbohydrate arabinogalactan, and essential oils. A sweet exudate known as "Briancon manna" appears on the foliage in summer, and a similar sweet substance can be tapped from the trunk; the inner bark has historically been eaten raw or ground into flour for bread in times of scarcity. Bark tannins were once used in leather tanning, while preparations of bark and resin have been used in folk medicine as expectorants for chronic bronchitis and in treatments for urinary and rheumatic complaints. Larch is one of the Bach flower remedies. Beyond the workshop and the apothecary, several species are widely used in bonsai and prized as ornamentals for their brilliant autumn colour, and larch ring records are central to dendrochronology in the boreal zone.
Taxonomy
The genus Larix Mill. was published by Philip Miller in Gardener's Dictionary Abridged, 4th edition, in 1754, and is the type genus of subfamily Laricoideae within Pinaceae. GBIF and other major checklists recognise the genus as accepted, with about 10 to 14 species depending on treatment; the Gymnosperm Database accepts eleven species plus the naturally-occurring hybrid Larix × czekanowskii. The species fall into three broad geographic groups — North American, northern Eurasian, and southern Asian (Sino-Himalayan) — and recent molecular work suggests the deepest phylogenetic divide separates the high-latitude circumboreal species from the southern Asian taxa.
History
The genus was formally described by Philip Miller in 1754 in the 4th edition of his Gardener's Dictionary Abridged, but larches have been recognised and used much longer: Larix was the Roman name for the tree, and the English word "larch" is first recorded in 1548 in the writings of the English botanist William Turner. Larches have been valued for their durable timber across their range for centuries, and have figured in European silviculture as plantation trees — particularly the Dunkeld hybrid, developed from European and Japanese parent species — since the 19th and 20th centuries.
