Definitions

larch

larch

[lahrch]
larch, any tree of the genus Larix, conifers of the family Pinaceae (pine family), which are unusual in that they are not evergreen. The various species are widely distributed in the Northern Hemisphere. Needles of the larches are mostly borne in characteristic radiating clusters. A western American larch (L. occidentalis) achieves a great height, and its lumber is used for interior construction, ties, posts, and cabinetmaking. The American, or black, larch (L. laricina), commonly called also tamarack and hackmatack, ranges from the Arctic Circle to cold swamps in more temperate regions of the NE United States and is cultivated elsewhere for its beauty. The wood of this species has been used in shipbuilding and for posts, ties, and poles. The European larch (L. decidua) has long been valued for its durable wood and as a source of Venice turpentine. This tree, the Japanese larch (L. leptolepis), and the Siberian larch (L. sibirica) are also cultivated for ornament. The related golden larch is Pseudolarix amabilis. Larch is classified in the division Pinophyta, class Pinopsida, order Coniferales, family Pinaceae.

Any of about 10–12 species of coniferous trees that make up the genus Larix of the pine family, native to cool temperate and sub-Arctic regions of the Northern Hemisphere. Though the larch has the pyramid shape typical of conifers, it sheds its short, light-green, needlelike leaves in autumn. The most widespread North American larch, the tamarack, or eastern larch (L. laricina), matures in 100–200 years, may grow 40–100 ft (12–30 m) tall, and has gray to reddish-brown bark. Coarse-grained, strong, hard, and heavy, larch wood is useful in ship construction and for telephone poles, mine timbers, and railroad ties.

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Larches are conifers in the genus Larix, in the family Pinaceae. They are native to much of the cooler temperate northern hemisphere, on lowlands in the far north, and high on mountains further south. Larches are among the dominant plants in the immense boreal forests of Russia and Canada.

They are deciduous trees, growing from 15-50 m tall. The shoots are dimorphic, with growth divided into long shoots typically 10-50 cm long and bearing several buds, and short shoots only 1-2 mm long with only a single bud. The leaves are needle-like, 2-5 cm long, slender (under 1 mm wide). They are borne singly, spirally arranged on the long shoots, and in dense clusters of 20-50 needles on the short shoots. The needles turn yellow and fall in the late autumn, leaving the trees leafless through the winter.

Larch cones are erect, small, 1-9 cm long, green or purple, ripening brown 5-8 months after pollination; in about half the species the bract scales are long and visible, and in the others, short and hidden between the seed scales. Those native to northern regions have small cones (1-3 cm) with short bracts, with more southerly species tending to have longer cones (3-9 cm), often with exserted bracts, with the longest cones and bracts produced by the southernmost species, in the Himalaya.

Species and classification

There are 10-14 species; those marked '*' in the list below are not accepted as distinct species by all authorities. In the past, the cone bract length was often used to divide the larches into two sections (sect. Larix with short bracts, and sect. Multiserialis with long bracts), but genetic evidence (Gernandt & Liston 1999) does not support this division, pointing instead to a genetic divide between Old World and New World species, with the cone and bract size being merely adaptations to climatic conditions. More recent genetic studies have 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 (Semerikov & Lascoux 1999; Wei and Wang 2003, 2004; Gros-Louis et al. 2005); there is some 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.

Eurasian

Northern, short-bracted

Southern, long-bracted

North American

Most if not all of the species can be hybridised in cultivation. The best known hybrid is the Dunkeld Larch Larix × marschlinsii (syn. L. × eurolepis, an illegitimate name), which arose more or less simultaneously in Switzerland and Scotland when L. decidua and L. kaempferi hybridised when planted together.

Larch is used as a food plant by the larvae of a number of Lepidoptera species - see list of Lepidoptera that feed on larches.

Larches are prone to the fungal canker disease Lachnellula willkommii (Larch Canker); this is particularly a problem on sites prone to late spring frosts, which cause minor injuries to the tree allowing entry to the fungal spores.

Uses

Larch is a wood valued in for its tough, waterproof and durable qualities; top quality knot-free timber is in great demand for building yachts and other small boats, for exterior cladding of buildings and interior panelling. The timber is resistant to rot when in contact with the ground, and is suitable for use as posts and in fencing. The hybrid Dunkeld Larch is widely grown as a timber crop in northern Europe, valued for its fast growth and disease resistance.

Larch has also been used in herbal medicine; see Bach flower remedies for details.

In central Europe larch is viewed as one of the best wood materials for the building of residences. Planted on borders with birch, both tree species were used in pagan "sagged" cremations. One "sąg" (pronounced song) of wood was required for a cremation stack. Sąg is used today as a Polish forestry unit measuring approximately 3 × 1 × 1 m.

In Siberia young larch leaves are harvested in spring, preserved by lactobacillus fermentation, and used for salads during winter.

Larches are often used in bonsai culture, where their knobby bark, small needles, fresh spring foliage and especially autumn colour are appreciated. European Larch, Japanese Larch and Tamarack Larch are the species most commonly trained as bonsai.

Trivia

The tree mainly used as a running joke in Monty Python sketches (And now... Number one...) is the larch.

External links and references

  • Gymnosperm Database: Larix
  • Phillips, D. H., & Burdekin, D. A. (1992). Diseases of Forest and Ornamental Trees. Macmillan ISBN 0-333-49493-8.
  • Gernandt, D. S. & Liston, A. (1999). "Internal transcribed spacer region evolution in Larix and Pseudotsgua (Pinaceae)". American Journal of Botany 86 711–723.
  • Semerikov, V. L., & Lascoux, M. (1999). Genetic relationship among Eurasian and American Larix species based on allozymes. Heredity 83: 62–70.
  • Wei, X.-X., & Wang, X.-Q. (2003). "Phylogenetic split of Larix: evidence from paternally inherited cpDNA trnT-trnF region". Plant Systematics and Evolution 239 67–77.
  • Wei, X.-X., & Wang, X.-Q. (2004). "Recolonization and radiation in Larix (Pinaceae): evidence from nuclear ribosomal DNA paralogues". Molecular Ecology 13 3115–3123.
  • Gros-Louis, M.-C., Bousquet, J., Pâques, L. E., & Isabel, N. (2005). Species-diagnostic markers in Larix spp. based on RAPDs and nuclear, cpDNA, and mtDNA gene sequences, and their phylogenetic implications. Tree Genetics & Genomes 1 (2): 50–63. Abstract.

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