Endangered Plants and Ecosystems - Plants In Decline, The American Landscape, Endangered Forests, Wetlands, Plant Conservation, Ecosystems Approaches To Conservation

Well over half the threatened and endangered species listed with the U.S. Fish and Wildlife Service are plants. There are a total of 714 threatened and endangered flowering plants (713 U.S. species, 1 foreign species), 5 threatened and endangered conifers and cycads (3 U.S. species, 2 foreign species), 26 listed ferns and allied species (all U.S.), and 2 listed lichen species (both U.S.). Listed U.S. species are shown in Table 4.1, which lists flowering plants, and Table 4.2, which lists endangered conifers, ferns, and lichens. Because the status of most plant species has not been studied in detail, many more plants are probably in danger of extinction than appear on these lists.

Many factors contribute to the endangerment of plant species. Numerous species are the victims of habitat loss due to land and agricultural development. Others have declined due to pollution or habitat damage, or as a result of competition with invasive species. Still others have succumbed to introduced plant diseases. Finally, collectors or dealers often illegally seek rare, showy, or unusual plants, and have depleted populations through over-collection.

The preservation of plant species is important for many reasons. Not only are plants of aesthetic value, they are crucial components of every ecosystem on earth. Plants also serve several functions directly beneficial to humans. First, they provide genetic variation that is used in the breeding of new crop varieties—native plants provide genes that allow for adaptation to local environments, as well as resistance to pests, disease, or drought. In addition, plants are the source of numerous human medicines.