To discuss the native plants of the Palouse, we want to think about the flora. The flora is the collection of plants that grow in an area. The flora of the Palouse refers to all the plants that grow on the Palouse, including those that occur naturally in the region ("native flora") as well as those that are brought into an area by human activity ("introduced flora"). In the last 100 years, agriculture has dramatically altered the balance of native and introduced plants in the flora of the Palouse. This is a very rapid rate of floristic change, which is characteristic of the impact that human activities have on environmental features in general. We should not, however, consider the flora of the Palouse to have been stable in the time before settlers brought agriculture. Floras and other aspects of natural environments tend to change over time, although natural change, in the absence of catastrophes, tends to be slow and to occur over thousands or tens of thousands of years.