There are 752 plants on the US Fish and Wildlife Service plant species list. The list, which is updated daily, includes endangered and threatened plant species in the United States. On the website, www.fws.gov, are lists specific to each state. The definitions for these categories found there are, "An 'endangered' species is one that is in danger of extinction throughout all or a significant portion of its range. A 'threatened' species is one that is likely to become endangered in the foreseeable future."
Once a plant is listed, it is protected from removal and disturbance by people. It can be removed from the list if it recovers sufficiently. One threat to endangered native plants is from invasive non-natives planted in their habitat. The US Department of Agriculture maintains a list of noxious weeds and invasive plants at their website, plants.usda.gov.
Why does it matter if a native plant species disappears? Each native plant species has a purpose in its native habitat. It provides food or shelter or fulfills some other function in the web of life. Native forests throughout the world are in danger because they are being removed to make way for agricultural development. This affects the whole environment, since trees throughout the world are vital in capturing carbon dioxide. Fewer forests mean more global warming, which is a function of the amount of carbon dioxide in the atmosphere. Each flower and shrub has wildlife that depends on it, and it is dependent on wildlife for pollination and seed propogation.
Cork Oak Trees in the Mediterranean
Cork trees are the source of corks used in wine bottles. Harvesting the cork does not damage the trees. It creates jobs and is an important industry in the local economy. The cork oak forests provide habitat for birds and other wildlife. The trend today is toward the use of plastic corks or screw tops on wine bottles. If the cork industry declines sufficiently, the cork oaks will be cut down so that the land can be used for other purposes. This will result in the destruction of valuable forest, jobs and native plant habitat. World Wildlife Fund has a project to save these forests and this industry.
Many prescription and non-prescription drugs (an estimated 25 to 40 percent, according to libraryindex.com) are derived from plant species, and many of these plants are threatened or endangered. Like the old growth forests, these plants are found in areas that are being cleared for development and agricultural use. Increased use of medicinal plants has led to exploitation of the available sources. One example is the Pacific yew, which has been over-harvested to produce cancer treatment drugs.Tropical forests, the main source of plants used to produce medicines, are rapidly being destroyed.
Drug companies and governments are starting to work together to create pharmaceutical preserves for medicinal plant research.
Milkweed is an example of a flowering plant that is disappearing due to land development. This native weed used to be common along roadsides that are now sprayed with pesticides to eliminate weed growth, and in open fields that are now cultivated or covered with houses. The significance is that monarch butterflies will only lay their eggs on milkweed, as the hatching caterpillars eat the milkweed, which has toxins that help them to survive (birds learn not to eat the toxic monarchs). The monarch butterfly population has declined as a result of this habitat loss. Other butterflies also seek specific plants to lay eggs.
The US Forest Restoration Act of 2003 was amended in 2009 to increase the areas it can protect. Protection involves the thinning of forests to reduce the chance of devastating wildfires that destroy forests and property. When a forest burns it takes decades for it to regrow. Wildfires destroy trees, wildlife habitat and native plants as well as people's homes. Preserving forests in the US so that native trees and plants do not become endangered is critical to our environment.
As we increase the use of native plants and trees in landscaping, wildlife will benefit.
Awareness of the relationship between forests and global warming is beginning to make governments and corporations develop conservation and restoration plans.