Larch [English], mélèze, mélèze laricin [French:]; lärche [German]; larice [Italian]; Лиственница listvenitsa [Russian]; カラマツ karamatsu [Japanese], 落叶松属 [Chinese].
There are 11 species in this treatment:
Syn: Pinus Linnaeus p.p.; Abies A. L. de Jussieu (non Miller) (Dallimore et al. 1967).
The European and North American species and varieties are generally agreed upon, while there is some debate about assigning specific, subspecific or varietal ranks to the Asian taxa. Such debate has principally involved L. sibirica and L. gmelinii, which together have a vast range including a small disjunct region (sometimes segregated from L. gmelinii as L. principis-rupprechtii) and very extensive zones of hybridization with each other and with intraspecific varieties (Milyutin and Vishnevetskaia 1995). The taxonomic uncertainties are partly due to the lack of a recent monographic treatment of Larix: the last were in 1930 (Ostenfeld and Syrach Larsen 1930) and, in a Russian paper not then readily available in the west, 1972 (Bobrov 1972). Moreover, there are political and linguistic problems involved in sorting out taxa native to remote areas of Russia and China.
|A.||Species with exserted bracts (Sect. Multiseriales Patschke; type L. griffithiana):|
|1.||L. occidentalis & L. lyallii|
|2.||L. potaninii, L. griffithiana, L. himalaica, L. mastersiana|
|B.||Species with non-exserted bracts (Sect. Larix; type L. decidua):|
|4.||L. gmelinii, L. kaempferi|
This was an attractive (and largely traditional) breakdown of the genus until the molecular folks got involved. Currently (2007.10.22) I have assembled five such studies:
Semerikov and Lascoux (1999), using isozymes, find a clear differentiation between New World and Old World larches.
Gernandt and Liston (1999), studying the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region in seven species of Larix and five of Pseudotsuga, consistently grouped the three North American species against a Eurasian suite including L. decidua, L. griffithii, L. sibirica and L. kaempferi. They rejected the hypothesis that L. decidua is derived from a short-bracted Eurasian lineage.
Wei and Wang (2003) used pollen cpDNA to split 12 species of Larix into three sister clades, one including North American species, and the other two comprised of the short-bracted and long-bracted species of Eurasia except that L. sibirica was in the long-bracted clade. Follow-up work (Wei and Wang 2004) using the nrDNA ITS confirmed the Eurasian-North American division of the genus.
Gros-Louis et al. (2005) went deeper, using genetic markers from the nuclear, chloroplast, and mitochondrial genomes to study ten species. They delineated three large groups: the North American, North Eurasian, and South Asian taxa. There was one significant ambiguity: L. sibirica was grouped with South Asian species on the cpDNA tree, but with its North Eurasian congeners on the mtDNA tree.
Based on these studies, I propose the following as a conceptual hypothesis of Larix phylogenetics:
Deciduous trees with sparse, open crowns. Bark silver-gray to gray-brown on young trees, becoming reddish brown to brown, smooth initially, scaly to thickened and furrowed with age. Branches whorled; shoots strongly dimorphic; short (spur) shoots prominent on twigs 2 years or more old, each bearing leaves (needles), and often pollen cone, or seed cone; lateral long shoots (sylleptic branches) sometimes produced by current-year growth increments; leaf scars many. Buds rounded. Leaves in tufts of 10-60 on short (spur) shoots or borne singly on 1st-year long shoots, deciduous, ± flattened, with abaxial keel, sessile, base decurrent, sheath absent, apex pointed or rounded; resin canals 2. Pollen cones solitary, ovoid-cylindric, yellowish. Seed cones green, red or purple, maturing pale to dark brown in 4-7 months, persisting several years after seed release, erect, globose to ovoid, terminal on short shoots or lateral on 1-year-old long shoots, on a short leafy peduncle; scales persistent, circular to oblong-obovate, thin, tough and leathery, lacking apophysis and umbo; bracts included or exserted. Seeds winged; cotyledons 4-6. x=12" (Parker 1993, M.P. Frankis e-mail 1999.02.26).
Sect. Larix occurs in boreal circumpolar lowlands in Alaska, Canada and Russia, and at moderate to high altitudes in mountains south to NE USA, the Alps of Europe, Mongolia, NE China, N Korea and C Japan. Sect. Multiseriales occurs at high to very high altitudes in the Sino-Himalayan mountain system and the central Rocky Mts. (LePage and Basinger 1995, Schmidt and McDonald 1995).
See Larix occidentalis.
All species have been utilized, principally for dendroclimatic reconstruction, although there has been recent use of the North American and European taxa in ecological and ecophysiological research.
Some species of Larix are economically important for their hard, heavy, and decay-resistant wood (Parker 1993). Top quality knot-free wood ('boatskin larch') is in great demand for yacht building (M.P. Frankis e-mail 1999.02.26). Despite their popularity as garden trees, only a few have received any horticultural attention; some cultivars exist for the most commonly cultivated Old World larches, L. decidua Miller and L. kaempferi (Lambert) Carrière, but almost none for the North American species (Parker 1993). L. kaempferi is a popular bonsai subject in Japan (M.P. Frankis e-mail 1999.02.26).
See the species descriptions.
Larix was the Roman name for larch (Parker 1993).
Larches are widely used in forestry in cool-temperate to subarctic zones. L. sibirica has proved the most successful tree for use in Greenland, but L. decidua and L. kaempferi have received the greatest international attention. Most if not all hybrid combinations attempted have been successfully created; the hybrid L. decidua × L. kaempferi (L. × marschlinsii Coaz, syn. L. × eurolepis Henry nom. illeg.) is an important forest tree in Britain.
Gernandt, D. S. and A. Liston (1999). Internal transcribed spacer region evolution in Larix and Pseudotsgua (Pinaceae). American Journal of Botany 86: 711-723. www.amjbot.org/cgi/reprint/86/5/711.pdf, accessed 2007.10.22.
Gros-Louis, M.-C., J. Bousquet, L. E. Pâques and N.e Isabel. 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: Genetic markers from the nuclear, chloroplast, and mitochondrial genomes were developed to distinguish unambiguously among four larch species [Larix laricina (Du Roi) K. Koch, Larix decidua (Mill.), Larix kaempferi (Lamb.) Sarg., and Larix sibirica (Ledeb.)] used in intensive forestry in eastern North America. Nine random amplified polymorphic DNA (RAPD) fragments had good diagnostic value, and 3 out of 12 nuclear genes were found to harbor fixed interspecific polymorphisms implicating a total of 17 single nucleotide polymorphisms (SNPs) and 2 indels. The sequencing of five mtDNA introns (cox1-intron1, matR-intron1, nad1-intron b/c, nad3-intron1, and nad5-intron1) and four cpDNA regions (matK, trnL-intron, trnT-trnL and trnL-trnF intergenic spacers) resulted in the identification of 14 sites with fixed interspecific differences among the four species. Including the ten Larix species, one polymorphic site per 47 nucleotide sites sampled was observed for nuclear genes, one per 283 sites for cpDNA, and one per 374 sites for mtDNA. The phylogeny of the genus could be estimated from variation among the ten species detected in two cpDNA intergenic regions and four mtDNA introns. There was congruence between cpDNA and mtDNA phylogenies with three large groups delineated: the North American, North Eurasian, and South Asian taxa. The position of L. sibirica differed between organelle genomes. It was regrouped with South Asian species on the cpDNA tree, but with its North Eurasian congenerics on the mtDNA tree. To simplify the detection of diagnostic DNA sequence polymorphisms among the four main Larix species, cleaved amplified polymorphic sequence (CAPS) assays were developed from the polymorphisms identified in the various genomes. Seventeen primer-enzyme combinations were tested, and six were selected for their high level of informativeness. These new species-specific diagnostic markers should be useful for the certification of larch breeding materials and hybrid stocks used in intensive forestry in the northern hemisphere.
Miller, P. 1754. The Gardener's Dictionary, abridged edition 4, vol. 1.
Semerikov, Vladimir L and Martin Lascoux. 1999. Genetic relationship among Eurasian and American Larix species based on allozymes. Heredity 83(1): 62-70. Available: www.nature.com/hdy/journal/v83/n1/full/6885310a.html, accessed 2007.10.22.
Wei, X.-X. and Wang, X.-Q. 2003. Phylogenetic split of Larix: evidence from paternally inherited cpDNA trnT- trnF region. Plant Systematics and Evolution 239(1-2): 67-77. Abstract: A molecular phylogeny of Larix comprising 12 species was constructed from the sequence analysis of the paternally inherited cpDNA trnT-trnF region of 46 individuals. The most parsimonious tree split Larix into three sister clades: one clade was composed of two North American species, the other two were short-bracted and long-bracted species of Eurasia respectively except that L. sibirica was clustered in the long-bracted clade. The difference between the present cpDNA phylogeny and previous nrDNA ITS phylogeny in the position of L. sibirica seems to suggest that ancient cytoplasmic gene flow might exist between sections Larix and Multiserialis. The short-bracted L. laricina and long-bracted L. occidentalis have an identical sequence of the trnT-trnF region, which implies that the bract length divergence among North American larches might have occurred recently or chloroplast capture happened during the early differentiation of the two species. The cpDNA results also shed some light on the biogeography of Larix.
Wei, X.-X. and Wang, X.-Q. 2004. Recolonization and radiation in Larix (Pinaceae): evidence from nuclear ribosomal DNA paralogues. Molecular Ecology 13(10): 3115-3123.
Gower, Stith T., and James H. Richards. 1990. Larches: deciduous conifers in an evergreen world. BioScience 40:818-826.
Schmidt-Vogt, H. 1977. Die Fichte; Ein Handbuch in zwei Banden. Band I: Taxonomie, Verbreitung, Morphologie, Ökologie, Waldgesellschaften. Hamburg - Berlin.
Last Modified 2012-11-23