Larches are deciduous conifers in the genus Larix, of the family Pinaceae. Growing to as much as 60 m (195 ft) tall, they are native to the cooler regions of the Northern Hemisphere. They grow in lowland forests in the far north, and high in mountains further south. Larches are among the dominant plants in the boreal forests of Siberia and Canada, making them the most abundant genus of trees on earth. Larch wood is tough and relatively durable; it is used in boatbuilding, cladding, decking, garden furniture, fencing, and construction. Products extracted from larch include arabinogalactan (larch gum), rosin, turpentine, and an essential oil.
Etymology The English name larch was recorded in 1548 by the botanist William Turner. It derives from the German Lärche, in turn from the Middle High German larche, which is conjectured to derive from an unrecorded Old High German name for the tree, *larihha. That derives from the Latin name of the tree, Larix. The Latin name probably was borrowed from a Gaulish language spoken in the Alps.
Description
Habit and foliage The tallest species, Larix occidentalis, can reach 50 to 60 m (165 to 195 ft). Larch tree crowns are sparse, with the major branches horizontal and in whorls; the second and third order branchlets are roughly horizontal in some species, pendulous in others. Larch shoots are dimorphic, with needle-like leaves borne singly on long shoots with several buds, and in dense clusters of 20–50 needles on short shoots with only a single bud. Larch wood is resinous. The bark of young trees is smooth; that of older trees is thick and scaly. Larches are among the few deciduous conifers, which are usually evergreen.
Cones The male (pollen) cones are small, on the ends of shoots that die after pollination. The female (seed) cones are small, typically erect, and take 4–7 months to reach maturity after pollination. The seed scales spread apart when mature, allowing the winged seeds, two per scale, to fall out. The leaflike bract scales can be either long and visible (exserted) or short and hidden between the seed scales.
The chromosome number is 2n = 24, similar to that of most of the other species of the family Pinaceae.
Distribution The genus Larix is present in all the temperate-cold zones of the Northern Hemisphere, from North America to northern Siberia, passing through Europe, mountainous China and Japan. The larches are important forest trees of Russia, Central Europe, the United States and Canada. They require a cool and fairly humid climate, and for this reason, their distribution includes the mountains of the temperate zones, while in the northernmost boreal zones, they are also found in the plains. Larix grows further north than any other tree genus, in North America and Siberia reaching the tundra and polar ice. The larch species Larix gmelinii is the world's most northerly-growing tree, at 75° north in the Taymyr Peninsula.
The larches are pioneer species not very demanding of the soil and they are very long-lived trees. They live in pure or mixed forests together with other conifers or more rarely with broad-leaved trees. In 1965, larch constituted 40.2% of the forests of the Soviet Union and had a cumulative volume of 28,450 million m3 (28.45 cubic kilometres, or 6.8 cubic miles) of solid wood; by a wide margin, the most abundant genus of trees on earth.
Evolution
External phylogeny The genus Larix belongs to the subfamily Laricoideae, which includes the Douglas firs, genus Pseudotsuga. The genus Cathaya was included in some older studies, but based on transcriptome analysis, is now considered closer to Pinus and Picea. The split of Larix from Pseudotsuga occurred about 45 million years ago.
Taxonomy and internal phylogeny
The genus Larix was described by the English botanist Philip Miller in 1754. In the 20th century, cone bract length was used to divide the larches into two sections (sect. Larix with short bracts, and sect. Multiserialis with long bracts), but genetic evidence does not support this division, indicating instead that the cone and bract size are merely adaptations to climatic conditions. Late 20th century and early 21st century genetic studies proposed three groups within the genus, with a primary division into North American and Eurasian species, and a secondary division of the Eurasian into northern short-bracted species and southern long-bracted species; there was dispute over the position of Larix sibirica, a short-bracted species which is placed in the short-bracted group by some of the studies and the long-bracted group by others. Ten species and one natural hybrid of larch are accepted by Plants of the World Online (POWO), following the conservative treatment in Farjon (2010); several others are accepted by the Flora of China.
However, a 2025 study by Qiu and colleagues cast doubt on the species circumscriptions accepted by Farjon and the POWO; it showed that Larix himalaica is close to L. griffithii as geographic parsimony would predict (and not to L. potaninii as Farjon believed), and that L. speciosa is distinct and should be treated as a separate species. Conversely, they found that L. mastersiana was embedded within L. potaninii and may be best synonymised with it. Their results showed that the division between Old World and New World species as suggested by earlier studies is not correct, but rather, the primary divide is between the high-latitude circumboreal species, and the low latitude Sino-Himalayan species group, as shown in the cladogram.
Hybrids
Most larches can be hybridised in cultivation; these hybrids are not discussed by POWO as they are not of natural occurrence. Larix × marschlinsii Coaz (syn. L. × eurolepis), the Dunkeld larch, a hybrid of L. decidua × L. kaempferi, is by far the best known: it is of major importance in forestry in northern Europe. It arose more or less simultaneously in Switzerland and Scotland in 1901–1904. Other named hybrids include Larix × pendula (Sol.) Salisb. (L. decidua × L. laricina), and Larix × eurokurilensis Rohm. (L. decidua × L. gmelinii).
Ecology
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