Taxodium distichum
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 Bald Cypress forest in a central Mississippi lake
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| Taxodium distichum (L.) Rich. |
Taxodium distichum, also known as Bald Cypress, Baldcypress or Swamp Cypress, is a species of conifer native to the southeastern United States, from Delaware Bay south to Florida and west to southern Texas, and also inland up the Mississippi and Ohio Rivers north to southern Illinois and Indiana.
It is a large tree, reaching 30-45 m tall and with a trunk diameter of up to 3 m. The leaves are spirally arranged but twisted at the base to lie in two horizontal ranks, 1-2 cm long and 1-2 mm broad; unlike most other species in the family Cupressaceae, it loses the leaves in the winter months (hence the name 'bald'). The cones are green maturing gray-brown, globular, 2-3.5 cm in diameter, and disintegrate when mature to release the large seeds. The seeds are 5-10 mm long, the largest of any species in the cypress family, and are water-dispersed.
Bald Cypress occurs mainly along riparian (riverside) wetlands subject to periodic flooding by silt-rich 'brownwater' rivers, unlike the related Pond Cypress, which occurs in silt-poor blackwater rivers and ponds. Ancient Bald Cypress forests, with some trees over 1200 years old, once dominated swamps in the southeast US. The largest remaining stand of Bald Cypress is at Corkscrew Swamp Sanctuary, near Naples, Florida. These trees are around 500 years of age and some exceed 40m (130 ft) in height. The largest individual specimen is "The Senator", near Longwood, Florida; it is 35 m tall, and with a trunk diameter of 344 cm.
Bald Cypresses growing in swamps have a peculiarity of growth called cypress knees. These are woody projections sent above the ground or water that are part of the root system. Their function was once thought to be to provide oxygen to the roots, which grow in the low dissolved oxygen (DO) waters typical of a swamp (as in mangroves). However, there is little evidence for this; in fact, roots of swamp-dwelling specimens whose knees are removed do not decrease in oxygen content and the trees continue to thrive. Another more likely function is that of structural support and stabilization. Lowland, or swamp grown cypress which are flooded or flood prone, tend to be buttressed, as opposed to cypresses grown on higher ground which may grow with very little taper.
The natural northern limit of the species is not due to a lack of cold tolerance, but to specific reproductive requirements; further north, regeneration is prevented by ice damage to the year-old seedlings. If slightly larger young trees are planted, they are able to tolerate much lower temperatures, and can be grown as far north as Minnesota. It is also commonly planted elsewhere outside of its native range in other temperate regions of the world.
Bald Cypress wood has long been valued for its water-resistance. Still usable prehistoric wood is often found in swamps in New Jersey and occasionally as far north as New England although it is more common in the southeast. The somewhat mineralized wood is mined from some swamps in the southeast, and is highly prized for specialty uses such as wood carvings.
The Bald Cypress was designated the official state tree of Louisiana in 1963, and is considered by some to be a symbol of the southern swamps.
[edit] References and external links
- Conifer Specialist Group (1998). Taxodium distichum. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- Taxodium distichum images at bioimages.vanderbilt.edu
- Detailed article on Taxodium distichum
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 Bald Cypress forest in winter, showing "knees" and (brown) high flood level. Lynches River, Johnsonville, South Carolina |
 Knees of a Bald Cypress in Chester County, Pennsylvania |
 Leaf closeup |
