Plants that take water from groundwater through their roots for their water supply are called phreatophytes. Phreatophytes are often found in wetlands or along streams (called riparian plants), and even away from surface water in upland habitats. While these plants also may rely on soil water that is recharged by precipitation, or by surface waters at different types of the year, they are still considered groundwater dependent because groundwater provides a portion of their water needs.
Because plants can rely on groundwater or surface water during different seasons or during various stages of their lifecycle, their groundwater dependency can fluctuate. In addition, plants can respond differently to varying groundwater levels. If groundwater levels change rapidly, plants can lose access to groundwater and die. Gradual decreases in groundwater levels can sometimes allow plants time to grow roots deeper and access lower groundwater or to adapt to less water. If groundwater levels become inaccessible to native vegetation, the new groundwater conditions may favor opportunistic invasive plants that displace and degrade natural habitats.