There are many species of plants that have become endangered. The causes of endangered species of plants are similar to those of many endangered animals. Many conservation projects are used to try and replenish the endangered plants.
How Does a Plant Become Endangered?
There are many causes of endangered species of plants. The main cause of a plant to become endangered is loss of its natural habitat. This is 
mainly due to the expansion of man kind. As urban development increase, plants loose more and more of their natural habitat. Clearing land for pastures and agricultural purposes also cause plants to loose their habitat. Grazing animals are a large contributor to causing a plants endangerment.
Natural disasters can also cause a plant to become endangered. Wild fires are a large natural cause of a plant to loose its natural habitat. Certain weeds and pests can deplete the land needed for certain plant species to survive.
Plants can become endangered due to their collection for multiple purposes. When plants are collected for nurseries or florists the plant species number decreases. Plant collectors of rare plants also contribute to a plant becoming endangered.
How Does Endangerment Happen?
The multiple causes of endangered species of plants often occurs over time. Sometimes it is not known that a plant has become endangered until after it has become extinct. For many plant species, it is often too late to save that species, unless by chance, some seeds can be found. Often, when a plant species is discovered to be endangered the situation is extremely critical and fast action must be taken.
How Can a Plant Species be Conserved?
Many efforts can be made to conserve endangered plant species. One agency that strives to protect endangered plants is the Environmental Protection Agency. This agency researches and monitors endangered plant species.
Once a plant has become endangered, distribution of the plant to reestablish a plentiful population occurs. This involves preserving its natural habitat. Certain areas of land will become protected for this reason.
With the protection efforts in place against endangered plant species, many of the plants can later be taken off the endangered species list. It is vital when saving plant species that fast action has to occur. An endangered plant species can quickly become extinct if the efforts are not made. Rare plants are at a higher risk of extinction than other plants because of the unique beauty.
References:
“Endangered Plants” Queensland Government
“Threatened and Endangered Plants” NCRS
Brighamia Igsignis: http://commons.wikimedia.org/wiki/File:Brighamia_insignis_-_%27Olulu_-_stat-endangered_-_desc-whole_plant.jpg