have been measured to reach 3 m in five years, 21 m in 41 years, and 36 m in height in 96 years; height growth has largely ceased by the time the trees are 200 years old. Some individuals can live over 1,000 years. Determination of the age of an old tree may be difficult because of frequent missing or false rings of stemwood caused by variable and stressful growing environments. Bald cypress trees growing in swamps have a peculiarity of growth called cypress knees. These are woody projections from the root system project above the ground or water. Their function was once thought to be to provide oxygen to the roots, which grow in the low dissolved oxygen waters typical of a swamp (as in mangroves). However, evidence for this is scant; 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 structural support and stabilization. Bald cypress trees growing on flood-prone sites tend to form buttressed bases, but trees grown on drier sites may lack this feature. Buttressed bases and a strong, intertwined root system allow them to resist very strong winds; even hurricanes rarely overturn them. Many agents damage T. distichum trees. The main damaging (in some cases lethal) agent is the fungus Lauriliella taxodii, which causes a brown pocket rot known as "pecky cypress." It attacks the heartwood of living trees, usually from the crown down to the roots. A few other fungi attack the sapwood and the heartwood of the tree, but they do not usually cause serious damage. Insects such as the cypress flea beetle (Systena marginalis) and the bald cypress leafroller (Archips goyerana) can seriously damage trees by destroying leaves, cones or bark. Nutrias also clip and unroot young bald cypress seedlings, sometimes killing a whole plantation in a short amount of time. In 2002, the Indiana Department of Natural Resources identified T. distichum as a state protected plant with the status of Threatened. Globally, the species is listed as of Least Concern by the IUCN. Cultivation and uses The bald cypress is hardy and can be planted in hardiness zones 4 through 10 in the US. The species is a popular ornamental tree that is cultivated for its light, feathery foliage and orangey brown to dull red autumnal color. In cultivation it thrives on a