What makes a plant rare?

Plants are generally considered rare when they occur in such small numbers throughout their range that they may become endangered if their present environment worsens. This could mean that they are found in large numbers at very few locations, in small numbers at many locations, or the worst of both worlds: in small numbers at few locations.

Some plants are rare naturally for a variety of reasons. Unique combinations of soils and climate often result in plants specially adapted over time to these habitats. The diverse and unusual soils, climate, and geography of California has led to a large number of endemic species in our state. Many of these endemic species have limited distributions and are rare as well.

Plants can also become rare as a result of the actions of humans. Activities such as road building, housing developments, recreation, dams, agriculture, and timber harvest can lead to alterations in and loss of habitat for species. In extreme cases, this can even result in the extinction of plant species.

A number of technical terms from the Federal Endangered Species Act are used in this brochure to describe the status of a given species. The term endangered refers to a species in danger of extinction within the foreseeable future throughout all or a significant portion of its range. If a species is threatened, it is likely to become endangered in the foreseeable future in the absence of special protection and management efforts. A species of concern is one that refers that is believed to be in need of concentrated conservation actions, though those actions would still need to be determined.