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Larix lyallii
Parlatore 1863
Common NamesAlpine larch, mountain larch, tamarack (4), mélèze de Lyall (2).Taxonomic notesLarix lyallii and L. occidentalis ( Larix sect. Multiseriales ) are similar morphologically and have similar geographic ranges. Just how closely the two species are related has not been determined, but they probably originated from a common ancestor resembling L. potaninii Batalin (2). They may hybridize where their ranges overlap (1).First described by Scots naturalist David Lyall in 1858 (1). DescriptionTrees to 25 m tall with dbh to 120 cm; crown sparse, conic to irregular. Bark thin, smooth, yellowish grey when young; becoming furrowed and flaking into red- to purple-brown scales with age. Branches horizontal, occasionally pendulous, often gnarled and irregularly spaced, persistent on trunk when dead; twigs strongly white- to yellow-tomentose for 2-3 years. Buds tomentose, scale margins ciliate. Needles deciduous, in bunches of 30-40 on short shoots 2-3.5 cm × 0.6-0.8 mm, 0.4-0.6 mm thick, keeled abaxially, 2-angled adaxially, light green, turning golden yellow in autumn; resin canals 40-80 µm from margins, each surrounded by 6-10 epithelial cells. Ovulate cones elliptic, upright, red when young, turning purplish and then brown with age, 2.5-4(5) × 1.1-1.9 cm, on curved stalks 3-7 × 2.5-4 mm; scales 45-55, rounded, margins erose, abaxial surface tomentose at maturity; bracts tipped by awn 4-5 mm, exceeding mature scales by ca. 6 mm. Pollen 78-93 µm diam. Seeds yellow to purple, body 3 mm, wing 6mm (1, 2).RangeCanada: Alberta and British Columbia; USA: Washington, Idaho and Montana at 1800-2400 m (2). It is locally common on exposed northern subalpine slopes to timberline, often with very rocky soils. It has very low shade tolerance and, due to its thin bark, low fire tolerance (1). See also (7). Its deciduous habit confers resistance to winter desiccation, permitting this species to reach timberline elevations that may be far above other conifers, and to retain an erect growth form on those sites.Although the geographic ranges of Larix lyallii and L. occidentalis overlap considerably, elevational differences of 150 to 300m usually separate them. Some morphologically intermediate specimens have been collected from Washington and Montana (2). Big TreeHeight 29 m, dbh 191 cm, crown spread 17 m, in Wenatchee National Forest, WA (5).OldestA ring-counted age of 791 years for sample COL-6A collected from a stand above Colchuck Lake in the Alpine Lakes Wilderness of WA by C.J. Earle in 1986. This is a pith date, but on a scarred core that may be missing some rings in the early 1300s. The tree was only about 40 cm diameter at the core height, a fine illustration of the rule-of-thumb that exceptionally old trees tend not to be particularly large ones. Materials exist to crossdate at least 500 years of this record, but the chronology was never worked up. There's also a crossdated age of 728 years for a specimen from W Alberta collected by B.H. Luckman (6). I believe this is from a living tree, collected in the late 1980s or early 1990s.DendrochronologyMany collections from the North Cascades of WA and the Canadian Rockies. E.g., (3).EthnobotanyDue to its small size and remote occurrence, its principal values are scientific (see"Dendrochronology") and aesthetic. Few trees are lovelier, either in spring when the soft green of the needles contrasts with deep snowdrifts still covering the ground in this species' alpine habitat, or in autumn, when its golden foliage complements the red of huckleberries and the icy blue of the sky.ObservationsMany very fine stands are to be found in the eastern Cascade Mountains, including the Alpine Lakes, Glacier Peak and Pasayten Wildernesses, North Cascades National Park (WA), and Manning Provincial Park (BC).RemarksMountain goats, bighorn sheep and black and grizzly bears all feed in alpine larch stands. Blue grouse feed on the needles (1).
Citations(1) Parish et al. 1996 .(2) William H. Parker at the Flora of North America web site . (3) Colenutt, Margaret E. and Brian H. Luckman. 1991. Dendrochronological investigation of Larix lyallii at Larch Valley, Alberta. Canadian Journal of Forest Research 21: 1222-1233. (4) Peattie 1950 . (5) American Forests 1996 . (6) Brown 1996 . (7) Robert S. Thompson, Katherine H. Anderson and Patrick J. Bartlein. 1999. Atlas of Relations Between Climatic Parameters and Distributions of Important Trees and Shrubs in North America. U.S. Geological Survey Professional Paper 1650 A&B. URL= http://greenwood.cr.usgs.gov/pub/ppapers/p1650-a/pages/conifers.html, accessed 22-Jan-2000.
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