Google Earth Community: Redwoods Around The World

The Redwood family, Taxodiaceae, includes 13 species in 9 genera of both evergreen and deciduous trees of the Order Coniferales of the Class Gymnospermae. Formerly classed with the Taxodiaceae, botanists have moved Sciadopitys from the Taxodiaceae and assigned it family rank as, the Sciadopiteaceae.

All genera of the Taxodiaceae family except one are confined to the northern hemisphere (North America and east Asia). Athrotaxis is endemic to Tasmania. No extant genus of Taxodiaceae occurs on more than one continent.

All species and natural varietal forms total 21 distinct kinds of trees. North America has 5 species in three genera. Mainland east Asia has 4 species and 8 varietal forms in 5 genera. But if we count Asia, Taiwan, and Japan, 5 genera, 7 species, and 8 varietal forms. Taiwania and Cunninghamia, and Taiwania and Metasequoia are share habitat in China. No such mix of Taxodiaceae genera occurs elsewhere. However, three species of Athrotaxis are found in the forests of Tasmania, and two species of Taxodium grow in proximity in eastern North America.
The proximity of California's Coast and Sierra redwoods is more an evolutionary coincidence than any geographic imperative.

More than 50 fossil species have been described from the Tertiary Period, 12 my BP, although the oldest known fossil Taxodiums date from the Jurassic, about 160 my BP.

The Taxodiaceae includes some of the earth's largest and oldest trees. Heights of over 325 ft. have been recorded for Coast and Sierra redwoods in California, and trunk diameters of 29 ft., 25 ft., 20 ft., 17 ft., and 11 ft. are known for the following:

-Sierra Redwood
-Coast Redwood
-Taxodium
-Cryptomeria and
-Metasequoia, respectively.

Sierra Redwoods are known to live at least 3,300 years, and Coast Redwoods and Athrotaxis at least a thousand years or more, surpassed only by Bristlecone Pine (Pinus longaeva) of western North America at 5,000+ years, and Patagonian Cypress (Fitzroya cupressoides) of South America at 3,622 years. As to size, they may only have been matched at some point in time by Eucalyptus regnans of Australia, and Douglas's False Hemlock (Pseudotsuga menziesii) of western North America, and may even have been exceeded by fossil Taxodiaceae.

The cypresses are derived from their redwood ancestors with a suite of morphological characters that make them different in appearance, yet related. It is the most widely distributed of all gymnosperm families, occurring in diverse habitats on all continents except Antarctica, although all genera other than Juniperus have become highly restricted in their distributions from former geologic times.

The Junipers are a large number of species, several of which are localized, rare and endangered.

The Taxodiaceae species are mostly relics of widespread forests in prehistoric times. Many species of the Cupressaceae and Taxodiaceae are regarded highly by native cultures and modern societies. The redwoods in particular are made special by their rarity and antiquity as well as by their special place in human hearts. The interest in redwoods goes beyond scientific study or even practical use or conservation; it cannot exclude cultural history, general knowledge and understanding, curiosity, social advocacy and activism, and art.

Fossil cypresses occur from the Jurassic Period, 180-135 million years before present, about as old as the redwoods and older than the pines, firs, and true cedars. The ancestral line of Taxodiaceae goes back some 160 million years. Between 130 million and about 1 million years ago redwoods of many species thrived throughout the northern hemisphere sustained by a warm humid climate. By the close of the ice ages about 250,000 years before present, the Taxodiaceae forests were vastly reduced in distribution; some becoming isolated groves dependent on peculiar environmental conditions. The species are rare, ancient, and made special by human cultures. They exist as biological relicts and components of the earth's biosphere, and their most important aspect in association with humans is the commendable processes and outcomes of preservation. All of the redwoods are special to human cultures in one way or another. In particular, the Giant Sequoias of the Sierra Nevada Mountains of California are famously known for being the world's largest living things. The nearby Coast Redwoods are equally known for being the world's tallest living things. The Southern Redwoods, or so-called bald cypress, are what make the storied Bayous so picturesque. The Dawn Redwood, discovered in China in 1941, and known as a living fossil, is highly renown by botanists and ecologists. Taiwan Redwood is also now being considered a living fossil for reasons relating to its primitive cone and ovule development. The Japanese Redwood has long been revered in Japan just as the Coast Redwoods and Giants are in California. The remaining species are all protected under international conservation programs.

Taxodium and Glyptostrobus have commonly been called cypresses, Athrotaxis and Cryptomeria have been called cedars, and Cunninghamia, and Athrotaxis referred to as fir and pine. It is unfortunate that these trees are still locally known as cypress, fir, or pine, for they are all true redwoods and should be called such regardless of regional folk names. They are prime trees, majestic in stature, tall, with buttressed trunks and fine foliage. Not only are they unequaled in attractiveness, they are especially honorable creatures that deserve special veneration.___ 17 Files____________
Related Folders by spacecowboy2006: Discovery Of Giant Sequoias; Special Trees; A Trove Of Botanical Treasures; Horticultural Treasures.

Edited by spacecowboy2006 (03/22/08 05:44 PM)

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