Native species are those that have been growing here naturally, since before Europeans settled in this area. These plants are well-adapted to the local climate and soils as well as to the naturally occurring historic disturbance processes such as fire, flooding, and wind throw.
As such, when seen in nature or when used in landscape projects, these plants require little encouragement once they are established—there is no need to water, mow, fertilize, or otherwise coddle them!
In addition, when the appropriate species are used in a planting project, they tend to be very "well-behaved;" that is to say that they don't overrun a site as aggressive non-native species might.
Another wonderful benefit of native plant species is that since they've been growing in our landscape for hundreds or thousands of years, the animals that have been living here thrive on them! Insects such as butterflies and other pollinators, small mammals, and numerous bird species all flock to settings that are rich in native plant diversity.