Larch

Taxobox
name = Larch


image_width = 240px
image_caption = "Larix decidua" in autumn
regnum = Plantae
divisio = Pinophyta
classis = Pinopsida
ordo = Pinales
familia = Pinaceae
genus = "Larix"
genus_authority = Philip Miller
subdivision_ranks = Species
subdivision = About 12; see text

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.

pecies 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

* "Larix decidua" (syn. "L. europaea") European Larch. Mountains of central Europe.
* "Larix sibirica" Siberian Larch. Plains of western Siberia.
* "Larix gmelinii" (syn. "L. dahurica, L. olgensis") Dahurian Larch. Plains of eastern Siberia.
* "Larix kaempferi" (syn. "L. leptolepis") Japanese Larch. Mountains of central Japan.
* "Larix principis-rupprechtii" Prince Rupprecht's Larch *. Mountains of northern China (Shanxi, Hebei).

outhern, long-bracted

* "Larix potaninii" Chinese Larch. Mountains of southwestern China (Sichuan, northern Yunnan).
* "Larix himalaica" Langtang Larch *. Mountains of central Himalaya.
* "Larix mastersiana" Masters' Larch. Mountains of western China.
* "Larix speciosa" Yunnan Larch *. Mountains of southwest China (southwest Yunnan), northeast Myanmar.
* "Larix griffithii" (syn. "L. griffithiana") Himalayan Larch. Mountains of eastern Himalaya

North American

* "Larix laricina" Tamarack Larch or American Larch. Plains of northern North America.
* "Larix lyallii" Subalpine Larch. Mountains of northwest USA and southwest Canada, at very high altitude.
* "Larix occidentalis" Western Larch. Mountains of northwest USA and southwest Canada, at lower altitudes.

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: [http://www.conifers.org/pi/la/index.htm "Larix"]
*Phillips, D. H., & Burdekin, D. A. (1992). "Diseases of Forest and Ornamental Trees". Macmillan ISBN 0-333-49493-8.
*cite journal |quotes=no |author=Gernandt, D. S. & Liston, A. |year=1999 |title=Internal transcribed spacer region evolution in "Larix" and "Pseudotsgua" (Pinaceae) |journal=American Journal of Botany |volume=86 |pages=711–723 |url=http://www.amjbot.org/cgi/reprint/86/5/711.pdf |doi=10.2307/2656581
*Semerikov, V. L., & Lascoux, M. (1999). Genetic relationship among Eurasian and American "Larix" species based on allozymes. "Heredity" 83: 62–70.
*cite journal |quotes=no |author=Wei, X.-X., & Wang, X.-Q. |year=2003 |title=Phylogenetic split of "Larix": evidence from paternally inherited cpDNA trnT-trnF region |journal=Plant Systematics and Evolution |volume=239 |pages=67–77 |url=http://www.springerlink.com/content/el841ejf4mp639fv/ |doi=10.1007/s00606-002-0264-3
*cite journal |quotes=no |author=Wei, X.-X., & Wang, X.-Q. |year=2004 |title=Recolonization and radiation in "Larix" (Pinaceae): evidence from nuclear ribosomal DNA paralogues |journal=Molecular Ecology |volume=13 |pages=3115–3123 |doi= 10.1111/j.1365-294X.2004.02299.x
*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. [http://www.springerlink.com/content/gu218j762h2q3702/ Abstract.]