Several locations in the southern Umpqua Valley are home to serpentine barrens characterized by it's eponymous serpentine soil. A soil of extremes, serpentine soil is derived from ultramafic bedrock mainly composed of serpentinite which creates an unfriendly environment to most plants. A small number of plants are capable of withstanding serpentine soil's extreme conditions which includes a low calcium-magnesium ratio, a lack of nutrients essential for plant growth and high concentrations of heavy metals. Plants unique to serpentine soil are referred to as "Serpentine Endemics". The majority of Umpqua Valley endemic plants make their home in serpentine soils.
The term serpentine can refer to both serpentinite rock and its main component the mineral serpentine.