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. The wood is used in boatbuilding, cladding, decking, garden furniture, fencing, and construction. Products extracted from larch include arabinogalactan, rosin, turpentine, and an essential oil.

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 loaned from a Gaulish language spoken in the Alps.

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.

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.

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, they are found in the mountains of the temperate zones, while in the northernmost boreal zones, they are also found in the plains. Larch trees go further north than all, reaching in North America and Siberia 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.

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.