Wednesday, July 31, 2013

The most beautiful of all the California conifers: hemlock spruce (Tsuga pattoniana)

High-altitude trees typically are storm-beaten. The hemlock spruce, which may grow singly or in thickets above timberline at exposed ridge-tops, sometimes show a shrubby krummholz form—expressing its life history of cold and windy conditions. Beneath the zones of heavy wind-currents, taller specimen—from eighty to a hundred feet high and from two to four feet in diameter—are found [1]. John Muir introduced the hemlock spruce as follows [1]:
The Hemlock Spruce is the most singularly beautiful of all the California coniferæ. So slender is its axis at the top, that it bends over and droops like the stalk of a nodding lily.  The branches droop also, and divide into innumerable slender, waving sprays, which are arranged in a varied, eloquent harmony that is wholly indescribable. Its cones are purple, and hang free, in the form of little tassels two inches long from all the sprays from top to bottom. Though exquisitely delicate and feminine in expression, it grows best where the snow lies deepest, far up in the region of storms, at an elevation of from 9000 to 9500 feet, on frosty northern slopes; but it is capable of growing considerably higher, say 10,500 feet.
John Muir, 1894.

Muir includes a sketch of a nodding, storm-beaten hemlock spruce (forty-feet high, he writes) in his book.

The currently accepted scientific name for hemlock spruce is Tsuga mertensiana. Muir used Tsuga pattoniana, one of the synonymous binomials of interest in nomenclature history, which also include binomial combinations such as Pinus mertensiana, Pinus pattoniania, Hesperopeuce mertensiana and Hesperopeuce pattoniana [2]. Common-name synonyms are mountain hemlock, alpine hemlock and black hemlock. This species occurs in mountain ranges from Alaska to California including British Columbia's mountains, the Olympic Mountains in Washington, the Coast and Cascade Ranges of Oregon, the Sierra Nevada and the Rocky Mountains [3]. 

Keywords: conifers, Pinales, Pinaceae, scientific names, nomenclature, natural history, Sierra Nevada.

References and more to explore
[1] John Muir: The Mountains of California. The Century Company, New York, 1894. Note: see pages 146 to 149  in the Penguin Classics Book print of 1985 with an introduction by Edward Hoagland.
[2] The Gymnosperm Database: Tsuga mertensiana [].
[3] USDA Forest Service: SPECIES: Tsuga mertensiana [].

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